Definitions
What conversion factor allows you to change one substance into another?
Mole ratio
On complete combustion, a sample of gaseous hydrocarbon, Z, produced 1.76g of carbon dioxide and 0.72g of water.(Relative atomic mass: C=12; O=16; H=1)
How many moles of carbon dioxide were produced?
Moles of CO2=Mass of CO2(g)/R.M.M of CO2 (g/mol)
Mass of CO2=1.76g and R.M.M of CO2=12+(16x2)=44 g/mol
Therefore moles of CO2=1.76 g/
44 g/mol
=0.04 mol of CO2
How many oxygen atoms are there in 2.2 moles of Al(NO3)3?
In one molecule of Al(NO3)3, there are 3 nitrate (NO3) groups. Each nitrate group has 3 oxygen atoms, so there are 3 x 3 = 9 oxygen atoms in one molecule of Al(NO3)3.
To find the number of oxygen atoms in 2.2 moles of Al(NO3)3, use Avogadro's number (6.022 x 10^23):
2.2 moles × (6.022 x 10^23 molecules/mole) × 9 oxygen atoms/molecule = 1.19 x 10^25 oxygen atoms
Steps to find theoretical yield
1. balance equation
2. identify what the limit reactant and the excess reactant. Do that by converting into moles.
*You want to use the limit reactant
3. use the limit reactant and convert it into grams
What is the concentration of Na+ in 1.0M of NaCl?
In a 1.0 M solution of NaCl, the concentration of Na+ ions is also 1.0 M. This is because each molecule of NaCl dissociates into one Na+ ion and one Cl- ion in solution
The mass in grams of one mole of a substance?
Molar mass
On complete combustion, a sample of gaseous hydrocarbon, Z, produced 1.76g of carbon dioxide and 0.72g of water.(Relative atomic mass: C=12; O=16; H=1)
How many moles of carbon atoms are there in CO2 are there in 1.76g of carbon dioxide?
To find the moles of C atom in CO2, the mole ratio between C and CO2 is used. Since one Carbon atom produces one CO2 molecule.
So it is a 1:1 mole ratio between C and CO2 . The mole of CO2 =0.04 mol
Therefore, C: CO2
1:1
?:0.04 mol
So the moles of C atom is 1 x 0.04 mol=0.04 mol of C atoms
Balance the following chemical equation: H₂ + O₂ → H₂O
Count the atoms on each side of the equation:
Reactants: 2 H atoms and 2 O atoms
Products: 2 H atoms and 1 O atom
how to find the percent yield?
actual yield/theoretical yield x 100
Copper oxide reacts with sulfuric acid to make copper sulfate and water. In an experiment, 1.6 g of dry copper sulfate crystals are made. If the theoretical yield is 2.0 g, calculate the percentage yield of copper sulfate.
To calculate the percentage yield, you can use the following formula:
Percentage yield = (Actual yield / Theoretical yield) x 100
In this case, the actual yield is 1.6 g, and the theoretical yield is 2.0 g. Plugging these values into the formula:
Percentage yield = (1.6 g / 2.0 g) x 100 = 0.8 x 100 = 80%
The percentage yield of copper sulfate in this experiment is 80%.
When balancing a chemical equation, what is added or changed?
Coefficient
If 138g NO2 and 48g O2 are reacted, what mass (in grams) of N2O5 is produced if there is a 90% yield?
4NO2 + O2 2N2O5
Calculate moles of NO2 and O2:
moles of NO2 = 138g / (46g/mol) = 3 moles
moles of O2 = 48g / (32g/mol) = 1.5 moles
2. Determine the limiting reactant:
Using the stoichiometry of the reaction (4NO2 + O2), we can see that 4 moles of NO2 react with 1 mole of O2.
moles of O2 needed for 3 moles of NO2 = 3 moles NO2 * (1 mole O2 / 4 moles NO2) = 0.75 moles O2
Since we have 1.5 moles of O2, which is more than enough, NO2 is the limiting reactant.
3. Calculate moles of N2O5 produced:
moles of N2O5 = 3 moles NO2 * (2 moles N2O5 / 4 moles NO2) = 1.5 moles N2O5
4. Calculate the mass of N2O5 produced with 90% yield:
mass of N2O5 = 1.5 moles N2O5 * (108g/mol) * 0.9 = 145.8g
So, 145.8g of N2O5 is produced with a 90% yield.
Balance the hydrogen atoms first by placing a coefficient in front of H₂O: H₂ + O₂ → 2H₂O
Now, there are 4 H atoms and 2 O atoms on the product side.
how many particles, molecules, atoms are in 1 mole?
6.02x10^23
Determine the empirical and molecular formula for chrysotile asbestos. Chrysotile has the following percent composition: 28.03% Mg, 21.60% Si, 1.16% H, and 49.21% O. The molar mass for chrysotile is 520.8 g/mol.
1. Divide the percentage by the molar mass of each element:
Mg: 28.03% / 24.31 g/mol = 1.153 moles
Si: 21.60% / 28.09 g/mol = 0.769 moles
H: 1.16% / 1.01 g/mol = 1.149 moles
O: 49.21% / 16.00 g/mol = 3.076 moles
2. Divide each value by the smallest number of moles to get the mole ratio:
Mg: 1.153 / 0.769 = 1.50
Si: 0.769 / 0.769 = 1.00
H: 1.149 / 0.769 = 1.49
O: 3.076 / 0.769 = 4.00
3. Round the mole ratios to the nearest whole number:
Mg: 1.50 ≈ 3
Si: 1.00 ≈ 1
H: 1.49 ≈ 3
O: 4.00 ≈ 4
The empirical formula is Mg3SiH3O4.
To find the molecular formula, divide the molar mass of chrysotile by the molar mass of the empirical formula:
Molar mass of empirical formula: (3 × 24.31) + 28.09 + (3 × 1.01) + (4 × 16.00) = 145.93 g/mol
Molecular formula multiplier: 520.8 g/mol / 145.93 g/mol ≈ 3.57 ≈ 4 (rounded to the nearest whole number)
Multiply the empirical formula by the molecular formula multiplier: (Mg3SiH3O4)4
The molecular formula for chrysotile asbestos is Mg12Si4H12O16.
Which formula shows the simplest ratio in which atoms will combine?
Empirical Formula
How many moles of oxygen atoms are there in 350g CaCO3?
Calculate moles of CaCO3:
Molar mass of CaCO3 = 40g/mol (Ca) + 12g/mol (C) + 3 * 16g/mol (O) = 100g/mol
moles of CaCO3 = 350g / 100g/mol = 3.5 moles
2. Calculate moles of oxygen atoms:
In one molecule of CaCO3, there are 3 oxygen atoms. So, in 3.5 moles of CaCO3, there will be 3.5 * 3 moles of oxygen atoms.
Therefore, there are 10.5 moles of oxygen atoms in 350g of CaCO3.
Balance the oxygen atoms by placing a coefficient in front of O₂:
2H₂ + O₂ → 2H₂O
Now, there are 4 H atoms and 2 O atoms on both sides of the equation.
The balanced equation is: 2H₂ + O₂ → 2H₂O
What is the molar ratio between H2 and H2O?
The balanced chemical equation for the formation of water from hydrogen gas is:
2H₂ → 2H₂O
From the balanced equation, we can see that 2 moles of H₂ gas react to form 2 moles of H₂O. The molar ratio between H₂ and H₂O is therefore 2:2, which can be simplified to 1:1.
Equations are balanced in order to abide by which law?
Law of conservation of mass
How many grams of Fe2O3 could be produced if 3 moles of Fe is reacted to completion with excess O2?
4Fe + 3O2* 2Fe2O3
Calculate moles of Fe2O3 produced:
From the balanced equation (4Fe + 3O2 → 2Fe2O3), 4 moles of Fe react to form 2 moles of Fe2O3.
moles of Fe2O3 = 3 moles Fe * (2 moles Fe2O3 / 4 moles Fe) = 1.5 moles Fe2O3
2. Calculate grams of Fe2O3 produced:
Molar mass of Fe2O3 = 2 * 56g/mol (Fe) + 3 * 16g/mol (O) = 160g/mol
grams of Fe2O3 = 1.5 moles Fe2O3 * 160g/mol = 240g
So, 240g of Fe2O3 could be produced if 3 moles of Fe is reacted to completion with excess O2.