Answer:
The molarity of the sulfuric acid is 0.018 M
Explanation:
The molarity of a solution is the number of moles of the solute (sulfuric acid in this case) in a 1-liter solution.
Every 100 g of the solution, we have 95 g sulfuric acid because its concentration is 95% w/w.
With the density, we can calculate how many liters are 100 g of solution:
density = mass / volume
1.85 g / ml = 100 g / volume
volume = 100 g / 1.85 g/ml
volume = 54.1 ml or 0.0541 l
Now, we know that we have 95 g sulfuric acid in 0.0541 l solution. In 1 l, we have then:
1 l * 95g / 0.0541 l = 1.756 g sulfuric acid.
But we want to know how many moles sulfuric acid we have per liter. Then, using the molar mass, we can calculate how many moles there are in 1.756 g sulfuric acid:
1.756 g * 1 mol / 98.08 g = 0.018 mol
The molarity is 0.018 M
What mass (in grams) of iron is required to react with 7.0 L of oxygen at 1 atm and 0ºC in order to produce Fe3O4 according to the balanced equation below
Answer:
26.18 g
Explanation:
The molar volume of oxygen at 1 atm and 0ºC is 22.4 L/mol.
If you want to react 7 L it means you will use
7/22.4 = 0.3125 moles of oxygen
the balanced equation is 3 Fe + 2 O2 = Fe3O4
which means that 2 moles of oxygen reacts with 3 moles of iron
If you have 0.3125 moles of oxygen, 0.468 moles of iron will be needed.
Iron molecular weight is 55.84 and than, 0.3125 moles corresponds to a mass of iron equal to 26.18
To determine the mass of iron required to react with 7.0 L of oxygen, we need to use the balanced equation and the molar ratios between iron and oxygen.
Explanation:To determine the mass of iron required to react with 7.0 L of oxygen, we need to use the balanced equation and the molar ratios between iron and oxygen. The balanced equation for the reaction is:
4Fe + 3O2 → 2Fe2O3
From the equation, we can see that it takes 4 moles of iron to react with 3 moles of oxygen to produce 2 moles of Fe2O3. First, we need to convert the volume of oxygen to moles by using the ideal gas law. At 0 degrees Celsius and 1 atm, the volume can be calculated as follows:
V = nRT/P
V = (7.0 L)(0.0821 L/mol·K)(273 K) / (1 atm)
V = 17.109 moles
Next, we need to use the molar ratios to determine the moles of iron required. Since the ratio is 4 moles of iron to 3 moles of oxygen, we can set up a proportion:
4 moles Fe / 3 moles O2 = x moles Fe / 17.109 moles O2
Solving for x:
x = (4 moles Fe)(17.109 moles O2) / 3 moles O2
x = 22.812 moles Fe
Lastly, we can convert the moles of iron into grams using the molar mass of iron:
(22.812 moles)(55.85 g/mol) = 1276.06 grams
Therefore, approximately 1276.06 grams of iron is required to react with 7.0 L of oxygen to produce Fe3O4.
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How much solution could be heated to boiling by the heat evolved by the dissolution of 28.0 g of NaOH? (For the solution, assume a heat capacity of 4.0 J/g⋅∘C,
Answer:
104.11 of solution could be heated till boiling at 1atm
Explanation:
For calculating this value, we are going to calculate it according to water whose heat capacity is 4.184 J/gC. We are going to use the value of entalphy of solution of the NaOH (-44.51kJ/mol in water at 25 celsius).
So, we have a heat balance
[tex]Q_{water} = Q_{NaOH}\\ m_{H2O} Cp_{H2O}\Delta T = m{NaOH} \Delta H {solution}\\[/tex]
Now, we know we have to calculate the mass of water and we know that water was initially at 25ºC, so we are going to take it into 100ºC. We also know that the heat of solution is given at kJ mol, so we have to do a transformation of units so we have the correct answer. We are going to change kJ into J and moles into grams
[tex]-44.51 \frac{kJ}{mol} * \frac{1mol NaOH}{39.9gNaOH} *\frac{1000J}{1kJ} = -1115.54 \frac{J}{g} NaOH[/tex]
Now, changing the values into the heat balance we obtain
[tex]m_{water} = \frac{m_{NaOH}*\Delta H}{Cp*\Delta T}\\ m _{water} = 104.11 g H2O[/tex]
Put the following steps of the light reactions in the correct order:
1. Light excites an electron from photosystem I.
2. Light excites an electron from photosystem II.
3. Electrons reduce NADP+ to NADPH.
4. Electrons pass through an electron transport chain, which generates a H+ gradient used to make ATP.
Answer:
1st: Light excites an electrom from photosystem II
2nd: Light excites an electrom from photosystem I
3rd: Electrons pass through an electron chain, which generates a H+ gradient used to make ATP
4th: Electron reduce NADP+ to NADPH
Explanation:
While the light simultaneously excites both photosystems, it must first occur in photosystem II and then be able to transfer the e-energized to photosystem I
1st Step:
Within the photosystems we find different photosynthetic pigments, that is, capable of absorbing light. These pigments are classified according to the maximum absorption wavelengths.
When the light hits the photosystems they absorb it and the delocalized -e (electrons) are energized or "excited".
Then these energized ones are transferred to molecules within the membrane that houses the pigments.
The e- that takes the photosystem I are provided by the photosystem II
2nd and 3rd Step:
The -e energized from photosystem II are transferred to a transport chain of -e within the membrane containing the pigments. As these -e circulate, they lose energy that is used to translocate H + (protons).
The accumulation of H + within the membrane generates an electrochemical gradient.
H + return to the stroma through the enzyme ATP synthase. This operation is called chemosmosis.
This enzyme uses H + to catalyze the synthesis of ATP (ADP + Pi), a process called phosphorylation.
4th Step:
The e-energized of photosystem I are used to reduce NADP + and generate NADPH that are used in conjunction with ATP to generate "light independent reactions"
Those lost from photosystem I are replaced by e-de-energized from photosystem II, while those lost from photosystem II are replaced by e-released from water by photolysis.
Water is divided by the energy of light into H + (used in chemosmosis) and oxygen (released as a byproduct)
The correct order of the steps for the light reactions in photosynthesis is: Light excites an electron from photosystem II, electrons pass through an electron transport chain, excitation of an electron in photosystem I, and finally, the reduction of NADP+ to NADPH i.e. 2, 4, 1, 3.
Explanation:The correct order of the steps for the light reactions in photosynthesis is:
Light excites an electron from photosystem II.Electrons pass through an electron transport chain, which generates a H+ gradient used to make ATP.Light excites an electron from photosystem I.Electrons reduce NADP+ to NADPH.This process starts with the absorption of light in photosystem II, which excites electrons. These electrons pass through an electron transport chain that uses the energy from the electrons to pump H+ ions and establish a gradient. This H+ gradient is used to synthesize ATP. Finally, light is absorbed by photosystem I which leads to the reduction of NADP+ to NADPH.
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Is cheddar cheese an element, compound, homogeneous mixture, or heterogeneous mixture?
Answer:
compound
Explanation:
Answer: homogeneous
Explanation :
A given sample of a xenon fluoride compound contains molecules of a single type XeFn, where n is some whole number. Given that 8.06 1020 molecules of XeFn weigh 0.227 g, calculate n.
Answer: The value of n =2.
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given molecules}}{\text {Avogadro's number}}=\frac{8.06\times 10^{20}}{6.023\times 10^{23}}=0.0013moles[/tex]
0.0013 moles of [tex]XeF_n[/tex] weigh = 0.227 grams
Thus 1 mole of [tex]XeF_n[/tex] will weigh = [tex]\frac{0.227}{0.0013}\times 1=174.62[/tex] grams
Molar mass of [tex]XeF_n[/tex] = [tex]1(131.3)+n(19)=174.62[/tex]
[tex]n=2[/tex]
Thus the value of n =2
The xenon fluoride compound is likely XeF2. This was deduced by relating the given mass and number of molecules of the compound to its molar mass and Avogadro's number. The calculated molar mass fits best with that of XeF2.
Explanation:The subject of your question lies in the area of analytical chemistry, specifically in calculations involving the concept of the mole. Here we want to find the molecular formula for the xenon fluoride, XeFn using the data provided. We know the Avogadro's number which states that one mole of any substance contains 6.02 x 1023 molecules.
In this question, we're given that 8.06 x 1020 molecules of XeFn weigh 0.227 g. We can calculate the molar mass of this specific compound. To elaborate, if one mole weighs 'M' grams and contains 6.02 x 1023 molecules, then 0.227 g would have (0.227/M) moles or (0.227/M) x 6.02 x 1023 molecules. If we set this equal to 8.06 x 1020 and solve for 'M', the molar mass of the compound, we can calculate a value of approximately 169 g/mol.
Given that the molar mass of xenon (Xe) is about 131 g/mol and that of fluorine (F) is approximately 19 g/mol, we can reason that the molar mass of the compound XeFn is closest to that of XeF2, since 131 + 2(19) = 169 g/mol. Therefore, the xenon fluoride compound being referred to in the problem is XeF2.
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A solution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 21 torr at 39.9 degrees C. The vapor pressures of pure methanol and pure water at this temperature are 256 torr and 55.3 torr , respectively.
Is the solution Ideal? NO, it isnt.
What can you say about the relative strengths of the solute-solvent interactions compared to the solute-solute and solvent-solvent interactions?
a. the methanol-water interactions are stronger than the methanol-methanol and water-water interactions.
b. the methanol-water interactions are weaker than the methanol-methanol and water-water interactions.
Answer:
Based on the conditions given as vapor pressure is 256 torr,the methanol-water interactions are stronger than the methanol-methanol and water-water interactions is the correct option.
The solution of methanol and water is non-ideal as the actual vapor pressure is lower than the expected value from Raoult’s law, indicating that the solute-solvent interactions are stronger than those within the pure components.
Explanation:A solution of methanol and water with a mole fraction of water of 0.312 and a total vapor pressure of 21 torr at 39.9 degrees C is not displaying ideal behavior. In an ideal solution, Raoult's law predicts that the total vapor pressure is the sum of the partial pressures of the components, each calculated as the product of the pure component's vapor pressure and its mole fraction in the solution.
In this case, if we assume the solution is ideal, the expected vapor pressure would be higher because methanol and water have vapor pressures of 256 torr and 55.3 torr, respectively. The given total vapor pressure (21 torr) is significantly less than the expected value calculated using Raoult’s law, indicating that the solution exhibits non-ideal behavior.
This observation implies that the intermolecular interactions between methanol and water are stronger than those in the pure substances (methanol with methanol and water with water). Thus, the interactions in the mixture reduce the tendency to escape to the vapor phase, resulting in a lower total vapor pressure than predicted for an ideal solution.
One container of Tumsr costs 4.00 dollars. Each container has eighty 1.00 g tablets. Assume each Tumsr is 40.0 percent CaCO₃ by mass. Using only Tumsr, you are required to neutralize 0.500 L of 0.400 M HCl. How much does this cost? Assume you are able to purchase individual tablets. Express your answer in dollars.
Answer:
1.25 dollars.
Explanation:
The balanced reaction will be
[tex]2 HCL+CaCO_3----------> CaCl_2+H_2O+CO_2[/tex]
mole ratio of [tex]CaCO_3[/tex] and HCl is 1 : 2
mole of HCl will be as
0.500 L HCl × 0.4 mol/L = 0.2 mol HCl
moles of [tex]CaCO_3[/tex] will be as
0.2 mole HCl × 1 mol [tex]CaCO_3/2[/tex] mol HCl = 0.1 mol [tex]CaCO_3[/tex]
mass of [tex]CaCO_3[/tex] will be calculated as :
0.1 mol [tex]CaCO_3[/tex] × 100.1 g / 1 mol [tex]CaCO_3[/tex] = 10.01 g [tex]CaCO_3[/tex]
Now 40.0% [tex]CaCO_3[/tex] = [tex]\frac{40}{100}[/tex] = 0.4 [tex]CaCO_3[/tex]
mass of [tex]CaCO_3[/tex] / (80 tablets × 1 g /tablets × 0.4 = number of containers
[tex]\frac{10.01}{32}[/tex] = 0.3128125 (number of containers)
Cost = number of containers × $4.00
= 0.3128125 × 4.00
= $1.25
Cost would be $1.25.
From the illustration, the total cost of Tumsr would be 1.25 dollars.
Stoichiometric calculationFrom the equation of the reaction:
CaCO₃ + 2HCl -----------> CaCl2 + CO2 + H2O
Mole ratio of CaCO₃ and HCl = 1:2
Mole of 0.5 L, 0.4 M HCl = 0.5 x 0.4 = 0.2 moles.
Equivalent mole of CaCO₃ = 0.2/2 = 0.1 moles
Mass of 0.1 mole CaCO₃ = 0.1 x 100.09 = 10 grams
Each Tumsr contains 40% CaCO₃ by mass. Meaning that each contains 0.4 grams.
10/0.4 = 25 Tumsr
A container of Tumsr containing 80 tablets costs 4.00 dollars, each tablet will then cost:
4/80 = 0.05 dollars
25 Tumsr will then cost = 0.05 x 25 = 1.25 dollars
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If you had a 0.650 L solution containing 0.0120 M of Zn2+(aq), and you wished to add enough 1.34 M NaOH(aq) to precipitate all of the metal, what is the minimum amount of the NaOH(aq) solution you would need to add? Assume that the NaOH(aq) solution is the only source of OH−(aq) for the precipitation.
Answer:
11.6 mL
Explanation:
First we need to calculate the number of moles of Zn2+ present in the solution:
[tex]n=V*C\\n_{Zn^{2+}}=0.65*0.012=7.8x10^{-3}moles[/tex]
As the charge of ion zinc is 2+ and the charge of hydroxide is 1-, we need double moles of NaOH:
[tex]n_{NaOH}=0.0156moles[/tex]
As we have the concentration and the moles, we can calculate the volume:
[tex]V=\frac{n}{C} \\\\V=0.01164L=11.6mL[/tex]
Calculate the density of oxygen, O2, under each of the following conditions:
a) STP
b) 1.00 atm and 35.0°C
Express your answers numerically in grams per liter. Enter the density at STP first and separate your answers by a comma
Answer:
a) 1.43 g/L
b) 1.27 g/L
Explanation:
Oxygen is an ideal gas, so, using the ideal gas equation:
PV = nRT
Where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature (always in Kelvin!).
n = mass (m)/molar mass (MM), so:
[tex]PV = \frac{m}{MM}RT[/tex]
PVMM = mRT
[tex]PMM = \frac{m}{V} RT[/tex]
m/V is the density (d), so:
d = [tex]\frac{PMM}{RT}[/tex]
R = 0.082 atm.L/(mol.K) and MM of O2 = 2x 16 = 32 g/mol
a) for STP, P = 1 atm and T = 0ºC = 273 K
d = [tex]\frac{1x32}{0.082x273}[/tex]
d = 1.43 g/L
b) P = 1 atm and T = 35ºC + 273 = 308 K
d = [tex]\frac{1x32}{0.082x308}[/tex]
d = 1.27 g/L
As oxygen is an ideal gas, the ideal gas equation is as follows:
[tex]PV= nRT[/tex]
P = pressure, V = volume, n = number of moles, R = gas constant, and T = temperature. n= m/MM
Formula: [tex]d=\frac{PMM}{RT}[/tex]a) for STP, P = 1 atm and T = 0ºC = 273 K, putting values in formula gives d = 1.43 g/L.b) P = 1 atm and T = 35ºC + 273 = 308 K, putting values in formula gives d = 1.27 g/L.Thus, answers for calculated densities are 1.43g/L and 1,27g/L.
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the pH of a solution is a measure of the acidity or alkalinity of a solution. Water has a pH of 7 and, in general, acids have a pH less than 7 and alkaline solutions have a pH greater than 7. Find the pH of a solution with a hydronium ion concentration of 8×10−8 moles/liter.
Answer:
7.1
Explanation:
equation to calculate pH is
[tex]pH=-Log_{10}(a_{H^+})=-Log_{10}(8*10^-8) = -Log_{10}(8)-Log_{10}(10^{-8})=-0.9+8=7.1 [/tex]
An alloy is a mixture of metals. Suppose that a certain alloy is made by mixing 50 grams of an alloy that contains 52% copper with 78 grams of pure copper.a). How many grams are in the resulting mixture? __grams.b). What percentage of the resulting mixture is copper? ___%
a) The total weight of the resulting mixture is 128 grams.
b) The percentage of the resulting mixture is copper is 81.25% copper.
a) Weight of alloy with 52% copper = 50 grams
Weight of pure copper = 78 grams
Total weight of resulting mixture = Weight of alloy + Weight of pure copper
= 50 grams + 78 grams
= 128 grams
So, the resulting mixture contains 128 grams.
b) To find the percentage of copper in the resulting mixture, you can use the following formula:
Percentage of copper = (Total weight of copper / Total weight of mixture) × 100
Total weight of copper = Weight of copper in alloy + Weight of pure copper
= (52% of 50 grams) + 78 grams
= 26 grams + 78 grams
= 104 grams
Now, Percentage of copper = (104 grams / 128 grams) × 100
= 81.25%
So, the resulting mixture contains 81.25% copper.
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The resulting mixture weighs 104 grams and contains 25% copper.
Explanation:
To calculate the grams in the resulting mixture, we need to add the masses of the two components. The alloy contains 50 grams of a 52% copper alloy, which means it contains 0.52 * 50 = 26 grams of copper. The pure copper weighs 78 grams. Adding these two masses together, we get:
Total mass of resulting mixture = 26 grams + 78 grams = 104 grams
To calculate the percentage of copper in the resulting mixture, we need to divide the mass of copper by the total mass of the mixture and multiply by 100. Using the values we calculated earlier:
Percentage of copper in resulting mixture = (26 grams / 104 grams) * 100 = 25%
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The molecular weight of H2SO4 is:
49.078 g/mole
98.086 g/mole
194 296 armoe
Answer:
98.086 g/mole
What is the hydroxide ion concentration for muriatic acid (has a pH of 2.5)?
Answer:
The concentration of the hydroxide ion concentration for muriatic acid is 3.16 * 10^-12 M
Explanation:
Muriatic acid = HCl
pH = 2.5
pH = -log[H+]
pOH = 14 - pH
pOH = 14 - 2.5 = 11.5
pOH = -log [OH-]
11.5 = -log [OH-]
[OH-] = 10^-11.5
[OH-] = 3.16 * 10^-12 M
The concentration of the hydroxide ion concentration for muriatic acid is 3.16 * 10^-12 M
Question 1(Multiple Choice Worth 4 points)
(06.03 MC)
A 50.0 mL sample of gas at 20.0 atm of pressure is compressed to 40.0 atm of pressure at constant temperature. What is the new volume?
0.0100 mL
0.325 mL
25.0 mL
100. mL
Question 2(Multiple Choice Worth 4 points)
(06.03 LC)
Which of the following would cause an increase in the pressure inside a sealed container of gas?
A leak in the container
An increase in temperature
An increase in the size of the container
Removal of half of the gas
Question 3(Multiple Choice Worth 4 points)
(06.03 MC)
A gas at constant volume has a pressure of 2.80 atm at 400. K. What will be the pressure of the gas at 360. K?
2.52 atm
2.94 atm
3.11 atm
3.78 atm
Question 4(Multiple Choice Worth 4 points)
(06.03 MC)
A 6.0 L sample of nitrogen gas contains 0.50 mole of a gas. If enough gas is added to make a total of 0.75 moles at the same pressure and temperature, what is the resulting total volume of the gas?
2.3 L
4.8 L
7.5 L
9.0 L
Question 5 (True/False Worth 1 points)
(06.03 LC)
When a scientific theory has been tested and proved by the scientific community, it becomes a law.
True
False
Question 6 (Matching Worth 3 points)
(06.03 LC)
Match the name of each gas law to the properties it compares.
Match Term Definition
Boyle's law A) Temperature and volume
Charles's law B) Pressure and temperature
Gay-Lussac's law C) Pressure and volume
Answer:
Problem 1 = 25.0 ml
Problem 2 = Increase in temperature
Problem 3 = 2,52 atm
Problem 4 =
Problem 5 = true
Problem 6 =
Explanation:
1) v2 = v1P1/P2 = (50 x 20)/40 = 25.0 ml
2.- An increase in temperature because there is a direct relationship among pressure and temperature.
3.- P2 = P1T2/T1 = (2.8 x 360) / 400 = 1008/400 = 2,52 atm
4.- 7.5 L
5.- True
6.- Boyle's law C) Pressure and volume
Charles's law A) Temperature and volume
Gay-Lussac's law B) Pressure and temperature
The concept Boyle's law is used here to determine the new volume. The behaviour of the gases is mainly studied on the basis of gas laws. The new volume of the gas is 25.0 mL. The correct option is C.
What is Boyle's law?The Boyle's law states that at constant temperature, the volume of a given mass of gas is inversely proportional to its pressure. At constant temperature the product of pressure and volume of a given mass of gas is constant.
Mathematically the law can be expressed as:
1. V ∝ 1 / P
V = k. 1 / P
PV = k (Constant)
For two different gases, the equation is:
P₁V₁ = P₂V₂
V₂ = P₁V₁ / P₂
20.0 × 50.0 / 40.0
V₂ = 25.0 mL
The new volume of the sample of gas is 25.0 mL.
Thus the correct option is C.
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Rubidium has two naturally occurring isotopes, rubidium -85 ( atomic mass = 84.9118 amu; abundance = 72.15%) and rubidium -87 (atomic mass = 86.9092; abundance = 27.85%). Calculate the atomic weight of rubidium
Answer:
The answer to your question is: 85.458 amu
Explanation:
data
Rubidium-85 A = 84.9118 amu abundance = 72.15%
Rubidium - 87 A = 86.9092 amu abundance = 27.85%
Atomic weight = ?
Atomic weight = 84.9118(0.7215) + 86.9092(0.2785)
Atomic weight = 61.2538 + 24.2042
Atomic weight = 85.458 amu
Rubidium has two naturally occurring isotopes, rubidium -85 ( atomic mass = 84.9118 amu; abundance = 72.15%) and rubidium -87 (atomic mass = 86.9092; abundance = 27.85%). The atomic weight of rubidium is 85.46 amu.
How to calculate the average atomic mass of element ?To calculate the average atomic mass of element use this formula
Average Atomic Mass = f₁M₁ + f₂M₂
where,
f = Fraction of natural abundance of isotope
M = Mass number of isotope
Isotope Rubidium -85 (Atomic mass = 84.9118 amu and Abundance = 72.15)
Abundance = [tex]\frac{72.15}{100}[/tex]
= 0.7215
Isotope Rubidium- 87 (Atomic mass = 86.9092 amu and Abundance = 27.85%)
Abundance = [tex]\frac{27.85}{100}[/tex]
= 0.2785
Now put the value in above formula, we get:
Average Atomic Mass = f₁M₁ + f₂M₂
= (84.9118 × 0.7215) + (86.9092 × 0.2785)
= 61.26 + 24.20
= 85.46 amu
Thus from the above conclusion we can say that Rubidium has two naturally occurring isotopes, rubidium -85 ( atomic mass = 84.9118 amu; abundance = 72.15%) and rubidium -87 (atomic mass = 86.9092; abundance = 27.85%). The atomic weight of rubidium is 85.46 amu.
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Which of the following gases was most likely present in Earth’s earliest atmosphere?
a.nitrogen
b.hydrogen
c.argon
d.oxygen
Hydrogen was the most common gas in the Earth's early atmosphere. The introduction of oxygen happened much later with the process of photosynthesis. Despite being present later, oxygen was not a primary component of the initial atmosphere.
Explanation:The gas that was most likely present in Earth's earliest atmosphere was hydrogen. This is based on scientific research, which suggests that the early atmosphere of the Earth was predominantly composed of light gases like hydrogen and helium. Over time, the Earth's atmosphere evolved and changed due to various geological and biological processes.
For instance, the process of photosynthesis introduced oxygen into the atmosphere much later in Earth's history. It's also important to note that despite being present, oxygen was not one of the primary components of Earth's early atmosphere.
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question 2 Which describes an atom with a negative net charge?
A
It contains more electrons than protons.
B
It contains more protons than electrons.
C
It contains more neutrons than protons.
D
It contains more neutrons than electrons.
Answer:
B
It contains more protons than electrons.
Answer:
A It contains more electrons than protons.
Explanation:
An atom basically consists of three entities protons, electrons and neutrons.
While protons and neutrons are present inside the nucleus and contributes to the total mass of the atom, electrons remain outside the nucleus and only contribute -1 charge per electron.
In an atom, a proton has +1 charge and mass equivalent to 1 a.m.u, a neutron has 0 charge and mass equivalent to 1 a.m.u and an electron has -1 charge and 0 mass (negligible).
Atomic number of an atom = number of electrons in that atom = number of protons in that atom.
In a neutral atom, the number of electrons are equal to the number of protons so their positive and negative charges counter balance each other thereby making the atom neutral.
But, if an atom gains an electron from an atom of any other element then it will acquire a net negative charge.
For example, a chlorine atom (Cl) when gains an electron it becomes Cl⁻.
Cl + e⁻ → Cl⁻
Silicon crystals are semiconductors. Which of the following is a correct reason for the increase in the conductivity of Si crystals when a small fraction of Si atoms are replaced with those of a different element?a. P atoms introduce additional mobile negative charges.b. P atoms introduce additional mobile positive charges.c. Ge atoms have more electrons than Si atoms.d. Ge atoms are much smaller than Si atoms.
Answer:
a. P atoms introduce additional mobile negative charges
Explanation:
Silicon atoms have a valency of 4, this means that there are 4 electrons in their outermost orbital. Thus, in silicon crystals, each Si atom is connected to 4 different Si atoms.
When we replace a few of these Si atoms with P atoms, which have a valency of 5, 4 out of these 5 outermost electrons will be bonded with the surrounding Si atoms. The fifth electron would not be bonded, meaning it would be free to move, acting as a mobile negative charge carrier (See the picture below).
Just to be clear, regarding option c), it's true that Ge atoms have more electrons that Si atoms, however that it's not a reason for an increase in conductivity.
When a small fraction of silicon (Si) atoms in a crystal are replaced with a different element, such as phosphorus (P) or germanium (Ge), the conductivity of the crystal increases. This increase in conductivity is due to P atoms introducing additional mobile negative charges, which allow electrons to move freely and contribute to the conductivity. This is known as n-type doping.
Explanation:When a small fraction of silicon (Si) atoms are replaced with those of a different element, such as phosphorus (P) or germanium (Ge), the conductivity of the Si crystals increases. The correct reason for this increase in conductivity is that P atoms introduce additional mobile negative charges. These extra electrons from the P atoms are able to move freely within the crystal lattice, contributing to the conductivity of the material. This type of doping with impurities is called n-type doping, where the primary carriers of charge are negative electrons.
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A tank is filled with a mixture of helium, oxygen, and carbon dioxide. The pressure inside the tank is 101.3 kPa. What is the partial pressure of oxygen, given the following partial pressures? A. 16.9 kPa B. 17.2 kPa C. 84.1 kPa D. 101.3 kPa
p he=84kPa
p co2= 0.1 kPa
Answer:
b
Explanation:
Answer:
The answer to your question is p O2 = 17.2 kPa, letter b
Explanation:
Remember that in a mixture of gases, total pressure is equal to the sum of the pressure of individual gases.
Then
Pt = p He + p CO2 + p O2
Data
Pt = 101.3 kPa
pHe = 84kPa
pCO2 = 0.1 kPa
p O2 = ?
Substitution
101.3 = 84 + 0.1 + pO2
pO2 = 101.3 - 84 - 0.1
pO2 = 17.2 kPa
How much heat should be transferred when 38.2g of liquid brownie reacts with excess hydrogen gas to form hydrogen bromine? Is the heat being transferred from the system to the surroundings or from the surroundings to the system?
When a chemical reaction take up energy then this type of reaction is called endothermic reaction. Therefore, heat is being transferred from the surroundings to the system.
What is endothermic reaction?In chemistry there are various type of reaction out of which the two main types are the exothermic reaction and endothermic reaction.
Exothermic reaction is the one in which energy releases in form of heat respiration reaction is an example of exothermic reaction. In respiration food that we eat are broken down in glucose with release of energy.
Endothermic reaction is the one in which energy is taken out during the reaction. Photosynthesis is an example of endothermic reaction where sunlight energy is taken by the plants to make food.
H[tex]_2[/tex]+ Br[tex]_2[/tex]→ 2 HBr ΔH = 72.80 kJ.
72.80 kJ of heat should be transferred when 38.2g of liquid brownie reacts with excess hydrogen gas to form hydrogen bromine. Heat is being transferred from the surroundings to the system.
Therefore, heat is being transferred from the surroundings to the system.
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The question contains a typo and seems to refer to a chemical reaction between hydrogen gas and bromine to form hydrogen bromide. Without specific data on the enthalpy change, one cannot conclusively say how much heat is transferred or definitively whether the reaction is exothermic or endothermic.
The original question seems to have a typo referring to 'liquid brownie' reacting with hydrogen gas, which is non-sensical in a chemistry context. Assuming the question pertains to the reaction of hydrogen gas (H₂) with bromine (Br₂) to form hydrogen bromide (HBr), as per the given example:
H₂(g) + Br₂(g) → 2 HBr(g)
To determine how much heat is transferred during this reaction and whether the reaction is exothermic or endothermic, we need additional data such as the enthalpy change (ΔH) for the reaction, which is not provided in the question. In general, if ΔH is negative, the reaction is exothermic, meaning heat is transferred from the system to the surroundings. Conversely, if ΔH is positive, the reaction is endothermic, and heat is transferred from the surroundings to the system.
Given the typical nature of reactions between halogens and hydrogen, one could infer that the reaction is likely exothermic, but without specific data on enthalpy change, this is an educated guess.
Which ion has a charge of 2+?
A
an ion with 10 protons, 9 neutrons, and 8 electrons
B
an ion with 8 protons, 10 neutrons, and 8 electrons
C
an ion with 8 protons, 9 neutrons, and 10 electrons
D
an ion with 10 protons, 10 neutrons, and 10 electrons
The ion with a 2+ charge is the one with 10 protons, 9 neutrons, and 8 electrons because there are two more protons, which are positively charged, than electrons, which are negatively charged thus giving it a positive charge.
Explanation:The correct answer is A: an ion with 10 protons, 9 neutrons, and 8 electrons. The charge of an ion is determined by the difference in the number of protons (positive charges) and electrons (negative charges). Note that the numbers of protons and electrons match exactly in a neutral atom. Therefore, an ion with 10 protons and 8 electrons would have a charge of 2+, since there are two more protons than electrons, giving it an overall positive charge.
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An ion with a charge of 2+ is an ion with 10 protons, 9 neutrons, and 8 electrons (option A).
To determine which ion has a charge of 2+, we need to understand that an ion with a 2+ charge has lost two electrons compared to its neutral state. Let's examine the options:
A: An ion with 10 protons, 9 neutrons, and 8 electrons. There are 10 protons, but only 8 electrons, meaning this ion has lost 2 electrons. Thus, it has a charge of 2+.B: An ion with 8 protons, 10 neutrons, and 8 electrons. It is neutral because the number of protons equals the number of electrons.C: An ion with 8 protons, 9 neutrons, and 10 electrons. There are more electrons than protons, indicating a negative charge.D: An ion with 10 protons, 10 neutrons, and 10 electrons. It has an equal number of protons and electrons and is therefore neutral.The correct answer is A, as it is the only ion with a 2+ charge.
The molarity of an aqueous solution of hydroiodic acid, HI, is determined by titration with a 0.145 M potassium hydroxide, KOH, solution. If 45.7 mL of potassium hydroxide solution are required to neutralize 50.0 mL of the acid, what is the molarity of the hydroiodic acid solution?
Answer:
0.133 M
Explanation:
The volume of the solution is given, so in order to find concentration, the number of moles must be found, since C = n/V.
The balanced reaction equation is:
HI + KOH ⇒ H₂O + KI
Thus, the moles of KOH added to neutralize all of the HI will be equal to the moles of HI that must have been present.
The amount of KOH that was added is calculated as follows.
n = CV = (0.145 mol/L)(45.7 mL) = 6.6265 mmol KOH = 6.6265 mmol HI
Since HI and KOH are related in a 1:1 molar ratio, the same amount of HI must have been present.
Finally, the concentration of HI is calculated:
C = n/V = (6.6265 mmol) / (50.0 mL) = 0.133 mol/L = 0.133 M
The final molarity of the hydroiodic acid solution is 0.133 M.
To determine the molarity of the hydroiodic acid (HI) solution, we can use the relationship between the moles of HI and KOH used in the titration process. The balanced equation for the neutralization reaction is:
HI(aq) + KOH(aq) → KI(aq) + H₂O(l)
The reaction shows a 1:1 molar ratio between HI and KOH. Given the volume and molarity of the KOH solution, we can calculate the moles of KOH used:
Moles of KOH = Molarity of KOH × Volume of KOH (in liters) = 0.145 M × 0.0457 L = 0.0066265 mol
Since the ratio is 1:1, the moles of HI will be the same as the moles of KOH, which is 0.0066265 mol. Now we can find the molarity of the HI solution using the volume of HI solution:
Molarity of HI = Moles of HI / Volume of HI (in liters) = 0.0066265 mol / 0.0500 L = 0.13253 M
Therefore, the molarity of the hydroiodic acid solution is 0.133 M (rounded to three significant figures).
Please help infer a quantitative measurement that can be made from the scene shown. be sure to use at least one complete content related sentence.
Answer:
The length (quantitative measurement) of the pencil is 5.5
Explanation:
Quantitative measurement are type of measurements which result in numbers
with or without appropriate unit .
To obtain the length of the pencil , the pencil starts from 0 of the scale and ends at 5.5 , hence the value is 5.5.
Quantitative measurement in the picture is the LENGTH of the pencil shown in the picture.
The value of quantitative measurement obtained from the picture is 5.5 , therefore length of the pencil is 5.5 .
A phospholipid has a glycerol attached to a phosphate group and two fatty acid chains. The head is hydrophilic, and the tail is hydrophobic. Why are the tails all located in the interior?
Answer:
Because they are normally dissolved in water
Explanation:
The phospholipids can act as molecules that are carry inside or outside the cells, to transport it they are dissolved in another hydrophilic media, in this way the hydrophilic part can be in the outside part of the group of moleucles stick together like in cell membranes that are conformed by a double lipidic layer, in which the hydrophobic part it in the inside part. The cells normally are surrounded by different water solutions as the blood or another solutions.
Which disorder is characterized by slightly bluish/dark-purple skin discoloration, most easily seen in the nail beds and mucous membranes, due to an increased quantity of methemoglobin, hemoglobin not combined with oxygen in systemic blood.
Answer:
Cyanosis
Explanation:
Cyanosis is purplish or bluish discolouration of skin or the mucous membranes. The presence of the cyanosis occurs due to the increased quantity of the deoxyhemoglobin and the haemoglobin is not combined with the oxygen. The tissues near the surface of the skin become to have low oxygen saturation. The first signs of the cyanosis can be seen on lips or fingers or finger nails.
A student takes four samples of a white crystalline solid and places each in a well plate. On top of each sample, she carefully places 20 drops of mystery liquids A, B, C and D. Her results for each well are:
The solid dissolves quickly in liquid A.
The solid remains unchanged with the addition of liquid B.
The white solid remains, but dissolves very slowly in liquid C.
When liquid D is added, fizzing occurs and the well becomes warmer.
In which well does a chemical change occur?
Answer:
D) D
Explanation:
yes it is correct took the test
Answer:
The answer is A
Explanation:
I just got it correct on USA test Prep
Consider that a sample of a compound is decomposed and the masses of its constituent elements is as follows: 1.443 g Se, 0.5848 g O What would be the empirical formula for this compound?
Answer: The empirical formula is [tex]SeO_2[/tex].
Explanation:
So, the mass of each element is given:
Mass of Se = 1.443 g
Mass of O = 0.5848 g
Step 1 : convert given masses into moles.
Moles of Se=[tex]\frac{\text{ given mass of Se}}{\text{ molar mass of Se}}= \frac{1.443g}{79g/mole}=0.018moles[/tex]
Moles of O = [tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{0.5848g}{16g/mole}=0.036moles[/tex]
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For Se = [tex]\frac{0.018}{0.018}=1[/tex]
For O =[tex]\frac{0.036}{0.018}=2[/tex]
The ratio of Se: O = 1: 2
Hence the empirical formula is [tex]SeO_2[/tex].
Aluminum metal reacts with bromine, a red-brown liquid with a noxious odor. The reaction is vigorous and produces aluminum bromide, a white crystalline substance. A sample of 27g of aluminum yields 266.7g of aluminum bromide. How many grams of bromine react with 18.1g of aluminum?
Answer: The mass of bromine reacted is 160.6 grams.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
Given mass of aluminium = 18.1 g
Molar mass of aluminium = 27 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of aluminium}=\frac{18.1g}{27g/mol}=0.670mol[/tex]
The chemical equation for the reaction of aluminium and bromide follows:
[tex]2Al+3Br_2\rightarrow 2AlBr_3[/tex]
By Stoichiometry of the reaction:
2 moles of aluminium reacts with 3 moles of bromine gas
So, 0.670 moles of aluminium will react with = [tex]\frac{3}{2}\times 0.670=1.005mol[/tex] of bromine gas.
Now, calculating the mass of bromine gas, we use equation 1:
Moles of bromine gas = 1.005 moles
Molar mass of bromine gas = 159.81 g/mol
Putting values in equation 1, we get:
[tex]1.005mol=\frac{\text{Mass of bromine}}{159.81g/mol}\\\\\text{Mass of bromine}=(1.005mol\times 159.81g/mol)=160.6g[/tex]
Hence, the mass of bromine reacted is 160.6 grams.
Final answer:
To find out how many grams of bromine react with 18.1g of aluminum, we first determine the mass ratio from a previous reaction and then use that to calculate the mass of bromine. The proportional relationship indicates that approximately 159.8 grams of bromine would react with 18.1 grams of aluminum.
Explanation:
The student asks how many grams of bromine react with 18.1g of aluminum. The chemical reaction is similar in behavior to the reaction of aluminum with chlorine where aluminum bromide is formed. Given a previous reaction scale of 27g aluminum yielding 266.7g aluminum bromide, we use stoichiometry to find the grams of bromine reacting with 18.1g aluminum.
First, determine the molar mass of aluminum (Al) and aluminum bromide (AlBr3). Aluminum has a molar mass of approximately 27g/mol and aluminum bromide has a molar mass of roughly 267g/mol based on the atomic weights of aluminum (approximately 27) and bromine (approximately 80 per bromine atom, with three bromine atoms per molecule). Find the mole ratio of Al to AlBr3 from the balanced chemical equation, which is 2:2 (or 1:1 for simplicity). From the initial reaction scale, you can calculate the ratio of aluminum to bromine involved in the reaction.
Next, set up a proportional relationship:
27g Al : 266.7g AlBr3 = 18.1g Al : x g AlBr3
To solve for x (the mass of aluminum bromide produced from 18.1g of aluminum), cross-multiply and divide:
27g Al * x g AlBr3 = 18.1g Al * 266.7g AlBr3
x = (18.1g Al * 266.7g AlBr3) / 27g Al
x ≈ 177.7g AlBr3
Finally, determine the mass of bromine involved. Since 27g of Al produces 266.7g of AlBr3, the mass of bromine can be calculated by subtracting the mass of aluminum from the total mass of the product:
266.7g AlBr3 - 27g Al = 239.7g Br2
Now, calculate the mass of bromine that would react with 18.1g of Al using the same proportion:
27g Al : 239.7g Br2 = 18.1g Al : y g Br2
Cross-multiply and solve for y:
y = (18.1g Al * 239.7g Br2) / 27g Al
y ≈ 159.8g Br2
Therefore, approximately 159.8 grams of bromine would react with 18.1 grams of aluminum.
How many liters of softened water, containing a sodium concentration of 5.2×10−2 % sodium by mass, have to be consumed to exceed the FDA recommendation? (Assume a water density of 1.0 g/mL.)
Final answer:
To exceed the FDA's assumed sodium intake limit of 2,300 mg per day for an adult, one would have to consume approximately 44.23 liters of softened water with a sodium concentration of 5.2×10⁻²% by mass.
Explanation:
The question pertains to the consumption of softened water and its sodium concentration relative to the FDA recommendations for sodium intake. The FDA's recommended limit is not specified in the question, so for this explanation, we will assume a commonly referenced guideline limit of 2,300 mg sodium per day for an adult. The concentration of sodium in the softened water is given as 5.2×10⁻²% by mass. Given this and the density of water (1.0 g/mL), we can calculate the volume of softened water consumed that would exceed the FDA's recommended sodium intake limit.
If the softened water contains 5.2×10⁻²% sodium by mass, this means there are 0.052 grams of sodium in every 100 grams of the softened water. Since 1 mL of water weighs 1 gram, this also means there are 0.052 grams of sodium per 100 mL of water.
To find the volume (V) of water that contains 2,300 mg (2.3 grams) of sodium, we set up the following equation:
V (in mL) × 0.052 g/100 mL = 2.3 g.
Solving for V, we get:
V = (2.3 g × 100 mL) / 0.052 g
V = 44,230.77 mL.
Therefore, one would have to consume approximately 44.23 liters of this softened water to exceed the FDA recommendation for sodium intake.
What are the six most important chemical elements of life?a. Carbon, nitrogen, calcium, oxygen, phosphate, and iron b. Carbon, nitrogen, sulfur, hydrogen, iron, and magnesium c. Carbon, nitrogen, oxygen, hydrogen, phosphate, and sulfur d. Carbon, nitrogen, calcium, zinc, iron, and hydrogen e. Carbon, nitrogen, oxygen, calcium, phosphate, and hydrogen
Answer:
The six most important chemical elements of life are c. Carbon, nitrogen, oxygen, hydrogen, phosphate, and sulfur
Explanation:
Oxygen is the most abundant element and carbon is part of living organisms. Nitrogen is also abundant and hydrogen is a simple element that is found in all living organisms as well. Therefore, all of these 4 should be present in the answer. This excludes answers: a, b and d. The differences between c and e is that c includes sulfur while e includes calcium. Both include phosphate which is part of DNA and RNA. This leaves to decide which one is found in the highest concentration. Calcium is part of bones and compositions of several living organisms but sulfur is found in essential amino acids and it is necessary for bacteria and other microorganisms. So, c would be the correct answer.
Final answer:
The six most important chemical elements of life are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, which make up almost all of a cell's mass and are key components of biological molecules.
Explanation:
Important Chemical Elements of Life
The six most important chemical elements of life are commonly known as the building blocks of living organisms. They form essential structures within cells and are involved in a myriad of biological processes. The six elements are carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S). Combined, they constitute approximately 99% of the dry weight of cells and are the major components of nucleic acids, proteins, carbohydrates, and lipids. According to the options provided in the student's question and including the information above, the correct answer to the question is option c: Carbon, nitrogen, oxygen, hydrogen, phosphate, and sulfur.
Each of these elements plays a critical role:
Carbon (C) is the key component of all organic molecules, forming a backbone to which other atoms can bond.Hydrogen (H) is involved in the structure of organic molecules and is a key player in energy transfer within cells.Nitrogen (N) is a primary component of amino acids, which are the building blocks of proteins.Oxygen (O) is essential for cellular respiration, which is the process by which energy is produced.Phosphorus (P) is a component of ATP, the energy currency of the cell, and is also found in the backbone of nucleic acids.Sulfur (S) is found in some amino acids and vitamins and is critical for protein structure.