Unit Stoichiometry Mass-mass Calculations Worksheet 2 Answers
Unit stoichiometry is an essential concept in chemistry that involves calculating the quantities of reactants and products in a chemical reaction. Mass-mass calculations, in particular, involve determining the mass of one substance that reacts with or is formed from a given mass of another substance.
Question 1
The first question in the Unit Stoichiometry Mass-mass Calculations Worksheet 2 involves a reaction between magnesium (Mg) and hydrochloric acid (HCl) to form magnesium chloride (MgCl2) and hydrogen gas (H2). The balanced chemical equation for this reaction is:
Mg + 2HCl → MgCl2 + H2
The question provides you with the mass of magnesium (3.4 grams) and asks you to calculate the mass of hydrogen gas produced. To solve this problem, you need to use the molar mass of magnesium and hydrogen, as well as the stoichiometry of the reaction.
First, calculate the moles of magnesium using its molar mass (24.3 g/mol): 3.4 g Mg × (1 mol Mg/24.3 g Mg) = 0.14 mol Mg
Next, use the mole ratio from the balanced equation to find the moles of hydrogen: 0.14 mol Mg × (1 mol H2/1 mol Mg) = 0.14 mol H2
Finally, convert the moles of hydrogen to grams using the molar mass of hydrogen (2.02 g/mol): 0.14 mol H2 × (2.02 g H2/1 mol H2) = 0.28 g H2
Question 2
The second question in the worksheet involves the reaction between sodium hydroxide (NaOH) and sulfuric acid (H2SO4) to form sodium sulfate (Na2SO4) and water (H2O). The balanced chemical equation for this reaction is:
2NaOH + H2SO4 → Na2SO4 + 2H2O
You are given the mass of sulfuric acid (5.6 grams) and asked to calculate the mass of sodium sulfate produced. Similar to the first question, you need to use the molar masses of the substances and the stoichiometry of the reaction to solve this problem.
Start by finding the moles of sulfuric acid using its molar mass (98.1 g/mol): 5.6 g H2SO4 × (1 mol H2SO4/98.1 g H2SO4) = 0.057 mol H2SO4
Apply the mole ratio from the balanced equation to determine the moles of sodium sulfate: 0.057 mol H2SO4 × (1 mol Na2SO4/1 mol H2SO4) = 0.057 mol Na2SO4
Convert the moles of sodium sulfate to grams using its molar mass (142.0 g/mol): 0.057 mol Na2SO4 × (142.0 g Na2SO4/1 mol Na2SO4) = 8.1 g Na2SO4
Question 3
The third question in the worksheet involves the reaction between nitrogen gas (N2) and hydrogen gas (H2) to form ammonia (NH3). The balanced chemical equation for this reaction is:
N2 + 3H2 → 2NH3
You are given the mass of nitrogen gas (7.8 grams) and asked to calculate the mass of ammonia produced. Follow the same steps as in the previous questions to solve this mass-mass calculation problem.
Calculate the moles of nitrogen gas using its molar mass (28.0 g/mol): 7.8 g N2 × (1 mol N2/28.0 g N2) = 0.28 mol N2
Determine the moles of ammonia using the mole ratio from the balanced equation: 0.28 mol N2 × (2 mol NH3/1 mol N2) = 0.56 mol NH3
Convert the moles of ammonia to grams using its molar mass (17.0 g/mol): 0.56 mol NH3 × (17.0 g NH3/1 mol NH3) = 9.5 g NH3
Conclusion
Unit stoichiometry mass-mass calculations involve using the molar masses of substances and the stoichiometry of a balanced chemical equation to determine the masses of reactants and products in a chemical reaction. By following the steps outlined in this worksheet, you can practice and improve your skills in solving these types of problems. Remember to always balance the chemical equation before performing any calculations and pay attention to units and conversion factors to ensure accurate results.