identify two metalloids that have the same number of electrons shells krypton
B and Si
Ge and As
Sb and Te
B and At
Answer;
Ge and As.
Explanation;
Elements Ge and As belong in the same period as krypton.
Each row of the periodic table is called the period.
Elements in each period have the same number of electron shells.
These elements in the same period do not have similar properties- the properties change greatly across every period. Krypton is in period four therefore all the elements in period 4 have four electrons shells.
The ka of propanoic acid (c2h5cooh) is 1.34 × 10-5. calculate the ph of the solution and the concentrations of c2h5cooh and c2h5coo– in a 0.193 m propanoic acid solution at equilibrium.
The pH and concentrations of C2H5COOH and C2H5COO– in a 0.193 M propanoic acid solution at equilibrium can be calculated using the given Ka and the formula for pH. The initial, change and equilibrium concentrations are used for these calculations.
Explanation:To calculate the pH and concentrations of C2H5COOH and C2H5COO– in a 0.193 M propanoic acid solution at equilibrium, we start by setting up the ICE (initial, change, equilibrium) table for the reaction. Ka = [H3O+][C2H5COO-] / [C2H5COOH], where H3O+, C2H5COO-, and C2H5COOH are equilibrium concentrations. Since the Ka for propanoic acid is given as 1.34 × 10-5, we can say that [H3O+] = sqrt(1.34 × 10-5 * 0.193).
We perform this calculation to find [H3O+], from which we find the pH = -log[H3O+]. The concentrations of C2H5COOH and C2H5COO– are both equal to 0.193 M in a 0.193 M solution of propanoic acid at equilibrium, as propanoic acid is a weak acid and partially ionizes in solution, leading to the same concentration at equilibrium.
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What does the frequency of a wave represent?
1. the distance between 2 consecutive crests
2. the number of wave cycles that pass through a specific point within a given time period
3. the distance between the highest and lowest points of a wave
4. the length of a wave that pass through a specific point within a given time period,
its actually answer 2
Select the correct text in the passage. Which sentence incorrectly describes the formation of petroleum
About 300 million years ago, the seas and oceans were inhabited by tiny plants and other organisms. These organisms died and were buried on the ocean floor. Over time, their bodies were covered with silt and mud that was rich in organic material, forming layers of organic matter. This matter was subjected to high temperature and pressure. In such conditions, oxygen was available in abundance. Over a period of many years, the matter decomposed and formed oil and gas.
the answer is: in such conditions, oxygen was available in abundance.
The rate constant is found to be 3.9 x 10-5 M-1 s-1. Calculate the rate of formation of ozone when the concentration of oxygen atoms is 3.0 x 10-14 molar and the concentration of diatomic oxygen is 1.3 x 10-14 molar.
If the Sun were much smaller than its current size, what effect would this have on eclipses?
The atoms and molecules in a liquid are in constant motion. As temperature decreases, what is true of the particles in the liquid? the rate of particle movement decreases the distance between the particles increases the attraction between the particles decreases the potential energy of the particles increases
a) The rate of particle movement decreases as temperature decreases, causing the atoms and molecules in the liquid to move less energetically.
The atoms and molecules in a liquid are in constant motion. As temperature decreases, the kinetic energy of these particles decreases as well.
This is because temperature is directly related to the average kinetic energy of the particles in a substance. Therefore, as the temperature drops, the particles move more slowly.
Here's a step-by-step explanation:
The decrease in the temperature of a liquid leads to a reduction in the thermal energy provided to the particles.
Kinetic energy, the energy of motion, is directly proportional to temperature, which measures the average kinetic energy of particles, indicating a decrease in temperature.
Particles' movement decreases with less kinetic energy, resulting in slower and slower particles.
The distance between particles may decrease due to stronger attractive forces at lower kinetic energies, but option b (distance increases) is incorrect as particles come closer together as they lose energy.
The attraction between particles decreases with decreased kinetic energy, causing them to pull closer together, contradicting option c.
Particles' potential energy decreases as they move closer in a stable configuration at lower temperatures.
Correct Question:
The atoms and molecules in a liquid are in constant motion. As temperature decreases, what is true of the particles in the liquid?
a) the rate of particle movement decreases
b) the distance between the particles increases
c) the attraction between the particles decreases
d) the potential energy of the particles increases
How many moles of NH4NO3(s) must be dissolved in water so that 73.0 kJ of heat is absorbed from the water? (The molar heat of solution of NH4NO3 is 25.7 kJ/mol.)
Answer:
2.84 mol
Explanation:
If the compound has a molar mass of 156 g/mol, what is its molecular formula?
The molecular formula of the compound is C10H20O.
The question is incomplete, the complete question is;
Menthol, the substance we can smell in mentholated cough drops, is composed of C, H, and O. A 0.1005-g sample of menthol is combusted, producing 0.2829 g of CO2 and 0.1159 g of H2O. What is the empirical formula for menthol? If the compound has a molar mass of 156 g/mol, what is its molecular formula?
First we have to obtain the mass/moles of each element;
Mass of C;
0.2829 g/44g/mol * 12 g/1 mol = 0.077 g of C
Number of moles of C = 0.077 g of C/ 12 g/mol = 0.0064 moles
Mass of H;
0.1159 g/18g/mol * 2g/1mol = 0.0129 g of H
Number of moles of H = 0.0129 g of H/1 g/mol = 0.0129 moles
Mass of O = 0.1005 g - (0.077 g + 0.0129 g)
Mass of O = 0.1005 g - 0.0899
= 0.0106 g
Number of moles of O = 0.0106 g/ 16 g/mol = 0.000663 moles
Dividing through by the lowest number of moles;
C - 0.0064/0.000663 H - 0.0129/0.000663 O - 0.000663/0.000663
C - 10 H - 20 O - 1
Empirical formula; C10H20O
Since the molecular formula is 156 g/mol
(C10H20O)n = 156
Where n is the number of each atom in the compound
(120 + 20 + 16)n = 156
156n = 156
n = 1
Hence the molecular formula of the compound is C10H20O.
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What volume of pocl3 gas can be produced in theory when 194 g of pcl3 gas reacts with excess oxygen?
Answer:
V = 2.28 L
Explanation:
What volume of pocl3 gas can be produced in theory when 194 g of pcl3 gas reacts with excess oxygen? at STP
1. Determine moles PCl3.
The reaction
2PCl3+O2--------->PClO3
mole =mass/molecular mass
194 grams/137.3334 grams/mole =
0.102 moles PCl3
2. Get the moles of POCl3 produced from 0.102 moles PCl3.
from the reaction above
2 moles PCl3 produce 2 moles POCl3
PClO3=0.102mole
3. Find the volume PClO3 using ideal-gas equation: PV = nRT
where:
P = pressure = 1 atm (standard pressure)
V = volume ?
n = moles PClO3 = 0.102 moles PClO3
R = gas constant = 0.08206 L*atm/mol*K
T = temperature = 273.15 K (standard temperature)
(1 atm)*V = (0.102 moles)*(0.08206 L*atm/mol*K)*(273.15 K)
V = 2.28 L
2. This graph can best be described as a
a. Bar graph
b. Exponential graph
c. Logistic growth graph
d. Line graph
Minerals are grouped into mineral classes primarily on a basis of _____. the number of cleavage directions present chemistry, specifically the cations within the chemical formula chemistry, specifically the anions within the chemical formula hardness; hard, soft, and medium are the three primary classes
An electric current can be conducted by _____. a sugar solution rubbing alcohol methane gas a salt solution
The answer is salt water.
Salt water can conduct electricity or we can say that an electric current is conducted by salt water as salt water is a good conductor of electricity when salt that is sodium chloride or NaCl is dissolved in water , positively charged sodium (Na⁺) and negatively charged chlorine(Cl⁻) molecules are set apart by the water molecule so that they can float easily and freely. We can define the conductivity of a substance as the mobility or movement of ions. So as in water, sodium and chlorine are set apart and can move freely so it become a electrolyte that can conduct electricity.
An electric current can be conducted by [tex]\boxed{\text{a salt solution}}[/tex].
Further Explanation:
Electric current:
The movement of charge carriers (electrons or protons) or ions is termed as electric current. In other words, rate of flow of electric charge through a point. SI unit of electric current is Ampere (A).
On the basis of different abilities of substances to conduct electric current, these can be classified as follows:
Conductors:
These materials allow smooth flow of charge carriers without any resistance in their movement and therefore these conduct heat and electricity.
Insulators:
These materials allow resistance to flow of electric charge carriers and therefore act as bad conductors of heat and electricity.
Semiconductors:
These allow movement of electric charge carriers under certain conditions. These have electric conductivity less than that of conductors but more than insulators.
Sugar solution cannot produce any ions in solution. Since no charge carriers are present in sugar solution, it cannot conduct electric current.
Rubbing alcohol does not contain free ions in it and therefore it cannot conduct electric current.
Methane gas is covalent in nature and does not have any free ions in it so it cannot conduct electric current.
Salt solution is nothing but solution of NaCl in water. NaCl is ionic compound so ions are present in salt solution and therefore it conducts electric current.
Therefore electric current can only be conducted by salt solution.
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Answer Details:
Grade: High School
Subject: Chemistry
Chapter: Metals and non-metals
Keywords: sugar solution, rubbing alcohol, methane gas, salt solution, electric current, electric charge carriers, conductors, insulators, semiconductors.
Suppose you want to make 100 grams of water, what is the molar mass of water
What might you expect to observe from this double-displacement reaction: CoCl2(aq) + Na2SO4(aq) ---> CoSO4 + 2NaCl?
Edit
A. CoSO4 precipitate will form.
B. NaCl precipitate will form.
C. one of these products will bubble out as a gas.
D. There will be no chemical change because there will be no chemical reaction; the ions will remain suspended in the water solution.
A reaction requires 22.4l of at stp. You have 32.0l of gas at 398k and 105.6 kpa. Will you have enough gas to carry out the reaction? True or false
To determine if you have enough gas to carry out a reaction, compare the gas volume at the given conditions to 22.4L at STP.
Whether you have enough gas to carry out the reaction can be determined by comparing the known volume at STP to the volume you have at the given conditions of 398K and 105.6 kPa.
If you have 32.0L of gas at 398K and 105.6 kPa, you need to calculate the volume that gas would occupy at STP using the ideal gas law and compare it to 22.4L, which is the volume needed for the reaction at STP.
If the volume at STP is greater than 22.4L, then you have enough gas to carry out the reaction. Otherwise, you do not have sufficient gas volume.
A. 50 g of nitrogen (n2) has a volume of ___ liters at stp.
Answer:
39.98 liters
Explanation:
The first you should know: At STP , 1 mole of any gas takes up 22.4 Liters of volume.
After, you will find the molecular weight (MW) of N2 with help of a periodic table.
Then N= 14,007 g
So:
N2 = 14,007 * 2
MW =28,014 g/ mol N2
Now you will start with the data of 50 grams of N2 and you obtain:
50 g N2 x 1 mol N2 x 22.4 L N2 = 39.98 L at STP 28,014 g N2 1 mol N2
50 g of nitrogen, N₂ has a volume of 40 L at standard temperature and pressure (stp)
We'll begin by calculating the number of mole in 50 g of N₂. This can be obtained as follow:
Mass of N₂ = 50 g
Molar mass of N₂ = 2 × 14 = 28 g/mol
Mole of N₂ =?Mole = mass / molar mass
Mole of N₂ = 50 / 28
Mole of N₂ = 1.786 moleFinally, we shall obtain the volume occupied by 1.786 mole of N₂ at STP. This can be obtained as follow:
At standard temperature and pressure (STP)
1 mole of N₂ = 22.4 L
Therefore,
1.786 mole of N₂ = 1.786 × 22.4
1.786 mole of N₂ = 40 L
Therefore, 50 g of N₂ occupies 40 L at standard temperature and pressure (STP).
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Carbonyl fluoride, cof2, is an important intermediate used in the production of fluorine-containing compounds. for instance, it is used to make the refrigerant carbon tetrafluoride, cf4 via the reaction 2cof2(g)⇌co2(g)+cf4(g), kc=8.90 if only cof2 is present initially at a concentration of 2.00 m, what concentration of cof2 remains at equilibrium?
Final answer:
To find the equilibrium concentration of COF2, we use the equilibrium constant Kc = 8.90 and set up a quadratic equation based on the initial concentration of COF2. Solving this gives us the concentration of COF2 remaining at equilibrium, which is approximately 1.58 M.
Explanation:
Equilibrium Calculation for Carbonyl Fluoride Reaction
To determine the concentration of COF2 that remains at equilibrium, we'll use the equilibrium constant and the initial concentration. The chemical equilibrium reaction is:
2COF2(g) ⇌ CO2(g) + CF4(g)
The equilibrium constant (Kc) for this reaction is 8.90. If only COF2 is present initially at a concentration of 2.00 M, let's define the change in concentration for COF2 at equilibrium as 'x'. This means at equilibrium, the concentration of COF2 will be (2.00 - 2x), and the concentrations of CO2 and CF4 will both be 'x' because they are produced in a 1:1 ratio.
The equilibrium expression is:
Kc = [CO2][CF4] / [COF2]2
Substituting the known values and expressions for equilibrium concentrations, we get:
8.90 = (x)(x) / (2.00 - 2x)2
This is a quadratic equation in the form of ax2 + bx + c = 0. By solving this quadratic equation, we can find the value of 'x' and therefore the equilibrium concentration of COF2. After calculation, the concentration of COF2 remaining at equilibrium is approximately 1.58 M.
Calculate the volume of 76.2 mole of propane gas,C3H8, if the molar volume is 55.0L/mol.
A certain object has a volume of 25.0 mL and a mass of 100 g. What is the density of the object?
Explain, in detail, how you convert grams of one substance to grams of something else. Be specific and include each step
Pseudoephedrine elixir contains 30 milligrams per teaspoon. The daily retail sales limit for pseudoephedrine is 3.6 grams. How many ounces of elixir is equivalent to 3.6 grams?
Answer:
Explanation:
Pseudoephedrine elixir contains 30 milligrams per teaspoon. The daily retail sales limit for pseudoephedrine is 3.6 grams. How many ounces of elixir is equivalent to 3.6 grams?
convert 3.6 grams to milligrams
3.6*1000
3600milligrams
but
30mg=1 teaspoon
3600mg=x teaspoon
120 teaspoon
but 1ounce=6 teaspoon
x=120 teaspoon
x=20 ounce
Therefore the daily limit of Pseudoephedrine elixir will be 20 Ounce
The philosopher Socrates was executed using which poison?
Answer:
Hemlock poison is your answer
Which is part of the hydrosphere? lightning plants clouds squirrels
The density of gasoline is 0.65 g/ml. what is the mass in kg of 45.0 l (about 12 gal) of gasoline?'
The mass of a substance can be determined from the density and volume of the substance. The mass of gasoline with 0.65 g/ml density and 45 L volume is 29.25 Kg.
What is density?Density of a substance is the measure of its mass per volume. Thus it is the ratio of its mass to the volume. Density of a substance depends on the temperature, pressure, bond type etc other than mas and volume.
Mass of the substance is the total amount of the substance expressed in g, kg or mg. The mass multiplied by the gravity experienced by the body is called its weight.
Volume of a substance is the total space occupied by the substance. Volume is expressed in cm³, Liter, milliliter etc.
Here the density of the substances is given 0.65 g/ml and volume is 45 liter or 45000 ml. Mass can be calculated by multiplying density with volume.
Mass = density × volume.
= 0.65 g/ml × 45000 ml
= 29250 g
= 29.25 g.
Hence, mass of the substance is 29.25 g.
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What mass of ammonia, NH3, is necessary to react with 2.1x10^24 molecules of oxygen in the following reaction?
4NH3(g)+7O2(g)+4NO2(g)
Final answer:
Approximately 1.998 moles of NH3 are required to react with 2.1x10^24 molecules of O2.
Explanation:
The balanced chemical equation for the reaction is:
4NH3(g) + 7O2(g) → 4NO2(g) + 6H2O(g)
From the equation, we can see that 4 moles of NH3 react with 7 moles of O2. Therefore, in order to find the mass of NH3 required to react with 2.1x10^24 molecules of O2, we need to convert the number of O2 molecules to moles and then use the mole ratio to calculate the moles of NH3 required.
Step 1: Convert 2.1x10^24 O2 molecules to moles:
Moles of O2 = (2.1x10^24 molecules) / (6.022x10^23 molecules/mol) = 3.49 moles O2
Step 2: Use the mole ratio from the balanced equation to find the moles of NH3 required:
4 moles NH3 / 7 moles O2 = (3.49 moles O2) * (4/7) = 1.998 moles NH3
Therefore, approximately 1.998 moles of NH3 are required to react with 2.1x10^24 molecules of O2.
Sensors detect the concentration of mercaptan molecules in natural gas at various distances from a leaking source. At which location will a sensor detect the highest concentration of mercaptan?
This is the answer but I need to know why this one.
(one-half meter in front of the source)
Calculate the percent composition of bromine in kBr
Final answer:
To calculate the percent composition of bromine in KBr, find the atomic mass of bromine and potassium, add them to get the formula mass of KBr, and divide the atomic mass of bromine by the total mass, then multiply by 100% to get the percentage.
Explanation:
To calculate the percent composition of bromine in KBr, you need to know the atomic masses of both potassium (K) and bromine (Br). KBr is made up of one potassium atom and one bromine atom. The atomic mass of potassium is approximately 39.10 amu (atomic mass units), and the atomic mass of bromine averages about 79.90 amu, accounting for its natural isotopic abundance.
The formula to find the percent composition is (mass of the element in one mole of the compound/mass of one mole of the compound) × 100%.
The total mass of one mole of KBr is the sum of the mass of potassium and the mass of bromine, which equals 39.10 + 79.90 = 119.00 amu. The percentage of bromine in KBr can be calculated as follows:
([tex]\frac{Mass of bromine}{Total mass of KBr}[/tex]) × 100% = ([tex]\frac{79.90 amu}{ 119.00 amu}[/tex]) × 100% ≈ 67.14%
Therefore, the percent composition of bromine in KBr is approximately 67.14%.
In an exothermic reaction, energy may be released to the surroundings in the form of
Explanation:
A reaction in which energy is released in the form of heat is known as exothermic reaction.
General reaction equation for exothermic reaction is as follows.
[tex]Reactants \rightarrow Products + Energy[/tex]
For example, lightening a candle is an exothermic reaction.
Thus, we can conclude that in an exothermic reaction, energy may be released to the surroundings in the form of heat.
By what factor does [h+ ] change for each ph change? (a) 3.20 units
Final answer:
The hydrogen ion concentration [H+] changes by a factor of 10 for each unit change in pH. Therefore, a pH change of 3.20 units results in a 10^3.20 (approximately 1,585-fold) change in [H+].
Explanation:
The pH scale is a logarithmic scale used to measure the acidity or basicity of an aqueous solution. The pH value is calculated by taking the negative logarithm of the hydrogen ion concentration ([H+]). For each unit change in pH, the hydrogen ion concentration changes by a factor of 10.
When considering a pH change of 3.20 units, you calculate the change in hydrogen ion concentration by raising 10 to the power of the pH change. Therefore, for each pH change of 1 unit, the [H+] changes by a factor of 10. Hence, for a change of 3.20 units:
A change of 1 unit corresponds to a 10-fold change in [H+].A change of 2 units corresponds to a 102 or 100-fold change in [H+].A change of 3 units corresponds to a 103 or 1,000-fold change in [H+].A change of 3.20 units corresponds to a 103.20 or approximately 1,585-fold change in [H+].For each pH change of 3.20 units, the [H⁺] concentration changes by a factor of approximately 1584.89.
A change of one unit on the pH scale represents a change in the [H⁺] concentration by a factor of 10. Consequently, a change of two units represents a change in the [H⁺] concentration by a factor of 100. For a change of 3.20 units, the factor is 103.20.
Calculating this, we get:
103.20 = 1584.89
Therefore, the [H⁺] concentration changes by a factor of approximately 1584.89 for a pH change of 3.20 units.