Number of particles
How many atoms are present in 2 moles of calcium (Ca)?
2 mol * (6.022 x 10^23 atoms/mol) = 1.2044 x 10^24 atoms.
What is the molar mass of carbon dioxide (CO2)?
Molar mass of CO2 = (Atomic mass of carbon) + (2 × Atomic mass of oxygen)
= 12.01 g/mol + (2 × 16.00 g/mol)
= 12.01 g/mol + 32.00 g/mol
= 44.01 g/mol
A compound contains 24 grams of magnesium (Mg) and 32 grams of oxygen (O). Determine its empirical formula.
The molar mass of Mg is 24.31 g/mol and O is 16.00 g/mol.
Moles of Mg = 24 g / 24.31 g/mol = 0.987 moles Moles of O = 32 g / 16.00 g/mol = 2.00 moles
0.987 / 0.987 ≈ 1
2.00 / 0.987 ≈ 2.02
The empirical formula of the compound is MgO.
In a chemical reaction, 25 grams of reactant A reacts to produce 18 grams of product B. Calculate the percentage yield of product B if the theoretical yield is 20 grams.
Percentage yield = (18 g / 20 g) × 100 = 0.9 × 100 = 90%
The percentage yield of product B is 90%
What is the molarity of a solution containing 25 grams of sodium chloride (NaCl) dissolved in 500 mL of water?
moles of NaCl = 25 g / 58.44 g/mol = 0.428 mol
500 mL is equal to 0.5 L
Molarity = 0.428 mol / 0.5 L = 0.856 M
The molarity of the solution is 1.0 M (mol/L)
How many atoms are present in 2.5 moles of carbon dioxide (CO2)?
using Avogadro's number 6.022 x 10^23 atoms/mol
Number of atoms = 2.5 moles * (6.022 x 10^23 atoms/mol) ≈ 1.5 x 10^24 atoms
There are approximately 1.5 x 10^24 atoms in 2.5 moles of carbon dioxide
What is the molar mass of sulfuric acid (H2SO4)?
Molar mass of H2SO4 = (2 × Atomic mass of hydrogen) + (Atomic mass of sulfur) + (4 × Atomic mass of oxygen)
= (2 × 1.01 g/mol) + 32.07 g/mol + (4 × 16.00 g/mol)
= 2.02 g/mol + 32.07 g/mol + 64.00 g/mol
= 98.09 g/mol
A compound is composed of 12.01 grams of carbon (C) and 16.00 grams of oxygen (O). Determine its empirical formula.
The molar mass of C is 12.01 g/mol and O is 16.00 g/mol.
Moles of C = 12.01 g / 12.01 g/mol = 1.00 moles Moles of O = 16.00 g / 16.00 g/mol = 1.00 moles
1.00 / 1.00 = 1 Moles
1.00 / 1.00 = 1 moles
The empirical formula of the compound is CO2.
0 grams of magnesium (Mg) reacts with excess hydrochloric acid (HCl) to produce 5.6 grams of magnesium chloride (MgCl2). If the theoretical yield is 8.0 grams, what is the percentage yield?
Calculate the percentage yield using the formula: (Actual yield / Theoretical yield) × 100
Percentage yield = (5.6 g / 8.0 g) × 100 = 0.7 × 100 = 70%
The percentage yield is 70%
What is the percent by mass of sucrose (C12H22O11) in a solution where 40 grams of sucrose is dissolved in 200 grams of water?
Mass of solution = 40 g + 200 g = 240 g
percent by mass of sucrose = (40 g / 240 g) × 100 = 16.7%
The percent by mass of sucrose in the solution is 16.7%
How many molecules are present in 4.8 moles of water (H2O)?
Use Avogadro's number to calculate the number of molecules
Number of molecules = 4.8 moles * (6.022 x 10^23 molecules/mol) ≈ 2.9 x 10^24 molecules
There are approximately 2.9 x 10^24 molecules in 4.8 moles of water
Determine the molar mass of calcium carbonate (CaCO3)
Molar mass of CaCO3 = (Atomic mass of calcium) + (Atomic mass of carbon) + (3 × Atomic mass of oxygen)
= 40.08 g/mol + 12.01 g/mol + (3 × 16.00 g/mol)
= 40.08 g/mol + 12.01 g/mol + 48.00 g/mol
= 100.09 g/mol
A compound is composed of 6.72 grams of nitrogen (N) and 1.344 grams of hydrogen (H). Determine its empirical formula.
The molar mass of N is 14.01 g/mol and H is 1.01 g/mol.
Moles of N = 6.72 g / 14.01 g/mol ≈ 0.479 moles Moles of H = 1.344 g / 1.01 g/mol ≈ 1.33 moles
0.479 / 0.479 = 1
1.33 / 0.479 ≈ 2.7
The empirical formula of the compound is NH3.
In a chemical synthesis reaction, 4.5 grams of compound X is produced. If the theoretical yield is 6.2 grams and the actual yield is 3.8 grams, what is the percentage yield?
Calculate the percentage yield using the formula: (Actual yield / Theoretical yield) × 100
Percentage yield = (3.8 g / 6.2 g) × 100 = 0.613 × 100 = 61.3%
The percentage yield is 61.3%
What is the molarity of a solution prepared by dissolving 8 grams of potassium hydroxide (KOH) in enough water to make a 500 mL solution?
moles of KOH = 8 g / 56.11 g/mol = 0.143 mol
500 mL is equal to 0.5 L
Molarity = 0.143 mol / 0.5 L = 0.286 M
The molarity of the solution is 0.32 M (mol/L)
How many ions are present in 0.5 moles of sodium chloride (NaCl)?
Number of ions = 0.5 moles * (2 * 6.022 x 10^23 ions/mol) ≈ 3.0 x 10^23 ions
There are approximately 3.0 x 10^23 ions in 0.5 moles of sodium chloride
What is the mass of 0.5 moles of sulfuric acid (H2SO4)?
0.5 mol * 98.09 g/mol = 49 g.
What is the molecular formula for glucose, given its empirical formula is CH2O?
12.01 g/mol for carbon) + (2 * 1.01 g/mol for hydrogen) + (16.00 g/mol for oxygen) = 30.03 g/mol.
180.18 g/mol.
180.18 g/mol ÷ 30.03 g/mol = 6
The molecular formula for glucose is C6H12O6.
Consider the balanced chemical equation: 2 H2 + O2 → 2 H2O. If 4 moles of hydrogen gas (H2) react completely, how many moles of water (H2O) will be produced?
the mole ratio between hydrogen gas and water is 2:2 (2 H2 : 2 H2O)
4 moles of hydrogen gas (H2) will produce 4 moles of water (H2O)
What is the mass/volume percent concentration of a solution if 25 grams of solute is dissolved in 150 mL of solvent?
(Mass of solute / Volume of solution) × 100
Mass/volume percent concentration = (25 g / 150 mL) × 100 = 0.1667 × 100 = 16.7%
The mass/volume percent concentration of the solution is 16.7
How many electrons are present in 1.2 moles of hydrogen gas (H2)?
Number of electrons = 1.2 moles * (2 * 6.022 x 10^23 electrons/mol) ≈ 1.45 x 10^24 electrons
There are approximately 1.45 x 10^24 electrons in 1.2 moles of hydrogen gas
Calculate the molar mass of sulfuric acid (H2SO4)
The atomic mass of hydrogen (H) is approximately 1.01 g/mol
The atomic mass of sulfur (S) is approximately 32.07 g/mol
The atomic mass of oxygen (O) is approximately 16.00 g/mol
= (2 * 1.01 g/mol) + 32.07 g/mol + (4 * 16.00 g/mol)
= 2.02 g/mol + 32.07 g/mol + 64.00 g/mol
= 98.09 g/mol
The molar mass of sulfuric acid (H2SO4) is 98.09 grams/mol
What is the molecular formula for ethene, given its empirical formula is CH2?
12.01 g/mol for carbon) + (2 * 1.01 g/mol for hydrogen) = 14.03 g/mol.
molecular formula mass = 28.05 g/mol
28.05 g/mol ÷ 14.03 g/mol = 2
The molecular formula for ethene is C2H4
In the reaction 2 Al + 3 Br2 → 2 AlBr3, if 0.5 moles of aluminum (Al) are completely reacted, how many moles of aluminum bromide (AlBr3) will be formed?
the mole ratio between aluminum and aluminum bromide is 2:2 (2 Al : 2 AlBr3)
0.5 moles of aluminum (Al) will form 0.5 moles of aluminum bromide (AlBr3)
What is the molarity of a solution prepared by dissolving 10 moles of solute in 2 liters of solvent?
Molarity (M) = Moles of solute / Volume of solution in liters
Molarity = 10 mol / 2 L = 5 M
The molarity of the solution is 5 M (mol/L)