Answer:
45.3 °C was the initial temperature
Explanation:
Step 1: explain the problem
We have to find the initial temperature, when a certain amount of heat raises this sample of water to its boiling point ( 100 °C)
⇒this amount of heat = 5.61 x 10^5 J
We will use the formule : Q = mcΔT
with Q = heat transfer ( J)
with m = mass of the substance (g)
with c = specific heat ( J/g °C)
with ΔT = change in temperature ( in °C or K)
The specific heat of water is 4.186 J/g °C
Step 2 : Calculate the initial temperature
To find the initial temperature, we have to rearrange the formule:
ΔT = Q / mc
In this case we have :
ΔT = 5.61 * 10^5 J / 2450 g * 4.186 J/g °C = 54.70
⇒ The final temperature of the water is the boiling point (100 °C). The change of temperature is 54.70 This means that the boiling point is 54.70°C higher than the initial temperature.
This means : ΔT = Tboiling point - Tinitial
ΔT = 54.70 °C = 100 °C - Tinitial
Tinitial = 100 °C - 54.70 °C = 45.3 °C
The initial temperature of the water is 45.3 °C
The atom in a chemical bond that attracts electrons more strongly acquires a(n)____________ charge, and the other atom acquires a(n)__________ charge. If the electron transfer is significant but not enough to form ions, the atoms acquire _____________ and charges. The bond in this situation is called a polar covalent bond.
Answer:
The answer to your question is below
Explanation:
The atom in a chemical bond that attracts electrons more strongly acquires a(n)__negative______ charge, and the other atom acquires a(n)_positive_______ charge. If the electron transfer is significant but not enough to form ions, the atoms acquire _dipoles_________ and charges. The bond in this situation is called a polar covalent bond.
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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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.
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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Is cheddar cheese an element, compound, homogeneous mixture, or heterogeneous mixture?
Answer:
compound
Explanation:
Answer: homogeneous
Explanation :
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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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.
Determine the mass of chloride (MW = 35.45 g/mol ) in grams present in 100 mL of a 0.273 M solution of aqueous FeCl₃ (iron(III) chloride). Express the mass in grams to three significant figures.
Answer:
The mass chloride is 2.903 grams
Explanation:
Step1: calculate the moles of FeCl3
moles = molarity x volume in liters
volume in liters = 100 ml /1000 = 0.1 L
molarity = 0.273 M = 0.273 mol / L
moles = 0.273 mol /L x 0.1 L = 0.0273 moles
step 2: find the moles of Cl
since there is 3 atoms of cl in FeCl3
= 3 x 0.0273 =0.0819 moles
Step 3: calculate mass of cl
mass= moles x molar mass
=0.0819 moles x 35.45 g/mol = 2.903 g
The mass of chloride in grams is 2.903 grams.
What is mass?Mass is defined as the quantitative measure of inertia, a fundamental properties of all the matter.
It can also be defined as the amount of matter present in any object or matter.
First calculate moles of FeCl3
Moles = Molarity x Volume in liter
Molarity = 0.273 mole / liter
Volume = 100ml = 0.1 l
Moles = 0.273 x 0.1 = 0.0273 moles
For FeCl3 3 molecules of Cl is needed
So, Moles of Cl = 3 x 0.0273
= 0.0819 moles
Now calculate the mass of Cl
Mass = moles x molar mass
= 0.0819 x 35.45
= 2.903 grams
Thus, the mass of chloride in grams is 2.903 grams.
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Question 7
Arsenic is a metalloid. Which statement best describes arsenic?
A
Arsenic is similar to a nonmetal because it is a gas at room temperature and similar to a metal because it is not malleable.
B
Arsenic is similar to a nonmetal because it is brittle and similar to a metal because it conducts heat and electricity well.
C
Arsenic is only similar to a metal because it is not ductile and is a gas at room temperature.
D
Arsenic is only similar to a nonmetal because it is a good conductor and is reflective.
Answer:
B.
Explanation:
It is brittle like a nonmetal but conducts electricity and heat like a metal.
Answer: The correct answer is Option B.
Explanation:
Metalloids are defined as the elements which show properties of both metals and non-metals. There are 7 metalloids in the periodic table. They are Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium and Polonium
Properties shown by metalloids:
They are semi conductors.They are amphoteric in nature.They show intermediate properties between metals and non-metals.Arsenic is a metalloid which belongs to Group 15 and Period 4 of the periodic table.
This element is brittle in nature and thus is similar to non-metals. Also, it conducts electricity and heat and thus is similar to metals.
Hence, the correct answer is Option B.
Identifying Physical and Chemical Changes.Matter has both physical and chemical properties and can undergo physical or chemical changes. Physical properties are those that a substance displays without changing its composition, whereas chemical properties are evident only during a chemical change (also called a chemical reaction). In contrast, when a substance undergoes a physical change, it may change appearance, but not its composition.Part A: Classify each of the changes as a physical change or a chemical change.Part B: Classify each of the properties as a physical property or a chemical property.
Answer: Part A: Physical change: Status changes of matter
chemical change: Any Chemical reaction
Part B: Physical property: Color, odor, etc
Chemical property: Flammability
Explanation:
Part A: A physical change: It´s change of form but not chemical composition.
Examples of Physical change are the Status changes of matter like boiling, melting, chooping wood, breaking a bottle and shredding paper.
A chemical change: It´s a change in the chemical composition of the compounds and generate new ones. That is called "chemical reaction" and it implies a rearrange of atoms generating new compounds.
Examples of chemical change are oxidation of Iron, burning, cooking, digesting food, rusting of iron.
Part B: Physical property: Are properties that can be measured or observed directly with our senses
Examples of physical Property: density,, appearance, texture, polarity, color, odor, melting point, solubility.
Chemical property: Are properties that can be observed when tey participate in a chemical reaction.
Examples of chemical Property: Reactivity , Radioactivity, Flammability , Acidity or basicity
Final answer:
A physical property of a substance can be observed without changing its chemical identity, such as melting point, while a chemical property, like flammability, involves a substance's propensity to change chemically. Physical changes do not alter a substance's chemical identity, unlike chemical changes which result in the formation of new substances.
Explanation:
Physical and Chemical Changes
Chemists categorize the properties of matter into physical and chemical properties. A physical property is an aspect of matter that can be observed or measured without altering the substance's chemical identity. Examples include color, density, melting and boiling points.
In contrast, a chemical property describes the substance's ability to undergo a specific chemical change, which alters its chemical composition. Flammability is a chemical property because it describes a substance's ability to burn, changing it into different substances as a result of this process.
Classifying Properties and Changes
Part A: One might observe a physical change when ice melts into water or when water vapor condenses - these are changes in state that do not involve altering the chemical identity of the substance. Chemical changes, however, such as the rusting of iron or the burning of wood, result in the formation of new substances.
Part B: Reflecting on the information given, properties like size, shape, and mass are physical, as they can be measured or observed without changing the material's chemical composition. In contrast, properties like reactivity with acids or the ability to oxidize would be classified as chemical properties, as they imply a change in chemical composition.
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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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.
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 .
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).
What is true about a positively charged ion?
It is formed when an atom loses electrons.
It is usually a nonmetallic element.
It has more electrons than protons.
It is formed when an atom gains protons.
The answer you're looking for is
It is formed when an atom loses electrons.
Explanation ??
Well, the electrons are the negative part of an atom right? And protons are the positive part of the atom! We learned that when all of us were younger and first learning about atoms. The main reason it isn't "It is formed when an atom gains protons" is because most atoms have protons, it can still be negative as long as it has more electrons than protons. So that leaves us with, "It is formed when an atom loses electrons." I believe this is correct because since it is losing electrons, it is losing the negativity!
(( Max ))
A positively charged ion is formed during reactions when an atom loses
electrons.
During chemical reactions, electrons are lost and gained as elements strive
to obtain a stable octet configuration. This is done through series of bonding techniques and processes such as covalent bond etc.
When an atom loses electrons it becomes a positively charged ion and
when an atom gains an electron it becomes negatively charged.
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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]
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
How do trans fats complicate the previous description of saturated and unsaturated fats?
A) Trans fats are unsaturated because they have one or more double bonds, but their molecules are straight due to that they have been generated from newly synthesized saturated fats.
B) Trans fats are unsaturated because they have one or more double bonds, but they have physical characteristics similar to saturated fats because they have almost the same amount of hydrogen atoms as saturated fats have.
C) Trans fats are unsaturated because they have one or more double bonds, but they have physical characteristics similar to saturated fats due to the trans double bond that straightens the hydrocarbon chain.
D) Trans fats are unsaturated because they have one double bond, but they have physical characteristics similar to saturated fats because they have only one double bond, which cannot change the physical characteristics signific
Answer:
C)
Explanation:
The fats can be saturated or unsaturated. Saturated fats have only simple bonds between atoms of carbon. The unsaturated fats have one or more double bonds between atoms of carbon.
When there are double bonds in the carbon chain, the molecule can have geometric isometric, if the carbons of the double bond have different binders. The isomers are named cis and trans. The cis molecule has the equivalent atoms or structures (the same or mass equivalent) on the same side of the plan of the molecule. The trans molecule has this equivalent atoms or structures in the opposite side of the plan of the molecule (see figure below)
It happens in a way to stabilize the molecule. So, the trans fat, because of its disposition, has straightened the hydrocarbon chain, almost like the saturated molecule, then, they have similar characteristics.
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]
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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The molecular weight of H2SO4 is:
49.078 g/mole
98.086 g/mole
194 296 armoe
Answer:
98.086 g/mole
What experiment can be used to separate suspended solid silver chloride from the water in which it is suspended?
Answer:
As the silver chloride is an insoluble compound in water, I can apply heat to water to make it evaporate and recover the chloride. You can also apply a filtration process to remove the liquid or centrifuge so the chloride can precipitate and remains at the bottom of the tube
Explanation:
Answer:
There are some physical separation methods that can help
Explanation:
Hi, given that the silver chloride is unsoluble in water it can be separated by physical means. Such as:
1) Filtration: this is the best option if you want to keep the water and not he salt.
Note: you can separate the salt from the filter by calcination
2) Centrifugal force: by applying centrifugal force to a test tube with the mixture, the unsoluble salt will precipitate.
3) Evaporation: if your product of interest is the salt, you can always apply heat to evaporate all the water. The salt will remain in the test tube.
A 10.00 g sample of a hydrocarbon (which is a compound that contains only carbon and hydrogen) was burned in oxygen, and the carbon dioxide and water produced were carefully collected and weighed. The mass of the carbon dioxide was 30.50 g, and the mass of the water was 14.98 g. What was the empirical formula of the hydrocarbon?
Answer:
C₅H₁₂
Explanation:
To obtain the answer for this question we need to do a combustion analysis. When a hydrocarbon is heated, it means that it reacts with oxygen (O₂) to produce two known products which are carbon dioxide (CO₂) and water (H₂O), and by knowing the masses of these products, we can know the proportions of the elements that initially were part of the hydrocarbon, in this case, the C/H ratio.
First, we propose the next reaction, assuming that all the hydrocarbon sample was combusted:
CxHy(s) + O₂(g) → xCO₂(g) + yH₂O(g)
Now, with the provided masses of the carbon dioxide and the water, we can calculate the molar amounts of carbon and hydrogen in the sample.
First we calculate the molar masses:
C = 12.011 x 1 = 12.011 g/mol
O = 15.99 x 2 = 31.99 g/mol
CO₂ = 12.011 + 31.99 = 44.001 g/mol
H = 1.008 x 2 = 2.016 g/mol
O = 15.99 x 1 = 15.99 g/mol
H₂O = 2.01 + 15.99 = 18.006 g/mol
Now we obtain the molar amounts of C and H using the obtaines masses of carbon dioxide and water:
mol C = 30.50g CO₂ x (1mol CO₂)/(44.001 g/mol) x (1mol C)/(1mol CO₂) = 0.6931 mol C
mol H = 14.98g H₂O x (1mol H₂O)/(18.006 g/mol) x (2mol H)/(1mol H₂O) = 1.6638 mol H
Finally, we can obtain the H/C molar ratio by identifying the smaller whole-number ratio for these molar amounts. For this we can first divide each molar amount by the smaller amount:
mol C = 0.6931/0.6931 = 1
mol H = 1.6638/0.6931 = 2.4
As we are still getting a decimal amount for the hydrogen, what we can do is multiply both molar amounts by the smaller whole multiple that can give us a whole number for the hydrogen's molar amount, in this case, that multiple would be 5:
mol C = 0.6931/0.6931 = 1 x 5 = 5
mol H = 1.6638/0.6931 = 2.4 x 5 = 12
Now we can write the empirical formula for the hydrocarbon, which is:
C₅H₁₂
Final answer:
To determine the empirical formula of the hydrocarbon, we need to calculate the moles of carbon and hydrogen in the sample. Once we have the moles of carbon and hydrogen, we can determine the empirical formula by finding the simplest whole number ratio between the two elements.
Explanation:
To determine the empirical formula of the hydrocarbon, we need to calculate the molar amounts of carbon and hydrogen in the sample. From the given masses of carbon dioxide (30.50 g) and water (14.98 g), we can determine the moles of carbon and hydrogen in the sample. The molar ratios of carbon and hydrogen in the compound will give us the empirical formula.
First, let's calculate the moles of carbon and hydrogen:
Moles of carbon = mass of carbon dioxide / molar mass of carbon dioxide
Moles of hydrogen = mass of water / molar mass of water
Once we have the moles of carbon and hydrogen, we can determine the empirical formula by finding the simplest whole number ratio between the two elements.
For example, if we find that the moles of carbon is twice the moles of hydrogen, the empirical formula would be CH2.
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⁻
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.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
Ammonium nitrate (NH4NO3) dissolves readily in water even though the dissolution is endothermic by 26.4 kJ/mol. The solution process is spontaneous because __________.
A. of the increase in disorder upon dissolution of this strong electrolyte
B. osmotic properties predict this behavior
C. of the increase in enthalpy upon dissolution of this strong electrolyte
D. the vapor pressure of the water decreases upon addition of the solute
E. of the decrease in enthalpy upon addition of the solute
Answer:
A.
Explanation:
For a process that occurs at constant temperature and pressure, spontaneity can be determined using the change in Gibbs free energy, which is given by:
ΔG = ΔH - TΔS. A process is spontaneous if ΔG≤O.
Even so the enthapy of the dissolution is positive the factor -TΔS will produce a negative ΔG value. As ΔS is relatived to the disorder of a system, a increase in this value (ΔS ) upon dissolution will made the dissolution process spontaneous.
The dissolution of NH4NO3 in water is endothermic but spontaneous due to the increase in disorder (entropy) when the compound dissolves and ionizes. This aligns with the second law of thermodynamics which states that systems tend towards increased disorder.
Explanation:The dissolution of ammonium nitrate (NH4NO3) in water is spontaneous despite being endothermic due to an increase in disorder or entropy upon dissolution. In a spontaneous process, the universe tends towards increased randomness or disorder, which is a central concept in the second law of thermodynamics.
When ammonium nitrate dissolves in water, it ionizes into its component ions, which increases the entropy of the system. The positive enthalpy change (which indicates endothermic dissolution) is offset by this sufficiently large increase in entropy, allowing the dissolution to be spontaneous even though it absorbs heat.
Therefore, the correct answer is option A: 'The solution process is spontaneous because of the increase in disorder upon dissolution of this strong electrolyte.'
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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].
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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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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