Assignment Question
Chapter 3 Assignment Spring 2023 1. Determine the Molecular Weight for the following: (round all to 2 decimal places) a. Pb(HSO4)2 __________ b. Al2(SO4)3 ______________ 2. Calculate Number of moles for the following: (2 decimal places for MW. Use proper number of significant figures for number of moles) a. 28.4g of Pb(NO3)2 No. moles _________________ b. 10.0g of calcium chloride No. moles _________________ Calculate the number of grams for the following. c. 2.750 moles of aluminum carbonate No. grams __________________ d. 0.0100 moles of bromine No. grams ________________ 3. Calculate the number of moles and number of atoms/molecules from the following: ( use correct number of significant figures for moles and atoms/molecules) Avogadro’s number is 6.022 x 1023 atoms/molecules per mole a. 8.0g of O2 No. moles _________________ No. molecules ________ total number of atoms______ b. 16.0g of magnesium phosphide No. moles _______ No. molecules ________ No. of Mg atoms________ No. of P atoms______ Total number of atoms ____________ There will be a problem like number 3 or 4 on EXAM 1. 4. Calculate the number of moles and grams from the following: (use correct number of significant figures and avogadro’s number from above) a. 1.48 x 1024 atoms of Ca No. of moles ________________ No. of grams _____________________ b. 6.487 x 1022 molecules of dinitrogen tetroxide No. of moles _________________ No. of grams _____________________ 5. Calculate the mass percent for each element in the following: WILL BE ON EXAM 1 a. Al2(SO4)3 b. C5H13O4N2 6. Use the mass percents to determine empirical formula: WILL BE on EXAM 1 a. Determine the empirical and molecular formula for the compound with a molar mass of 292.52 g/mol that contains 65.7% carbon, 21.9% oxygen, and 12.4 % hydrogen by mass. b. The composition of adipic acid is 49.3% C, 6.9% H, and 43.8% O (by mass). What is the empirical formula? What is the molecular formula for the compound with molar mass of 219.24 g/mole? 7. Balance each reaction and identify the type of reaction: ( combination (synthesis), decomposition, combustion.) a. Mg(s) + O2(g) → MgO(s) b. KClO3(s) → KCl(s) + O2(g) c.)___ C3H8(g) + O2(g) —-> ___ CO2(g) + ___ H2O(g) d.) ___ H2(g) + ___N2(g) —-> ____NH3(g) Stoichiometry. Use correct number of significant figures. (ALWAYS!!) SHOW ALL WORK!! 8. Mole to Mole Conversions (will be one exam 1) For a and b, calculate the number of moles of O2 present. Also identify the type of each reaction. combination, decomposition, or combustion. Reaction types will be on exam 1. How many moles of O2 react with 6.75 moles C2H6 ? a. 2C2H6(g) + 7O2(g) —-> 4CO2(g) + 6H2O(g) How many moles of O2 are produced by 6.75 moles of KClO3 ? b. 2KClO3(s) ——> 2KCl(s) + 3O2(g) Gram to Gram Stoichiometry (theoretical and percent yield) 9 . A student carried out the reaction shown by reacting 10.0g P4 with excess Cl2 and obtained an actual yield of 35.0g of PCl3 . Hint: Remember to balance the reactions first!! P4 + Cl2 —-> PCl3 a. What is the theoretical yield of PCl3? b. Calculate the % yield of PCl3. 10. A student wishes to attempt a chemical reaction that produces 10.0 grams of magnesium oxide. The student intends to mix magnesium metal and oxygen gas to produce the magnesium oxide. If oxygen gas is in excess, what mass of magnesium must the student use in the reaction to produce the desired 10.0 grams? Limiting Reactant and Theoretical Yield 11. Using the balanced equations, determine the limiting reactant and theoretical yield for each. Also identify the type of reaction for each. For a and b below: a.) Beginning with 100.0grams of Fe2O3(s) and 50.0 grams of CO, determine the limiting reactant and calculate the theoretical yield. Hint: Remember to balance the reaction first. a. Fe2O3(s) + CO(g) → Fe(s) + CO2(g) Calculate TY for Fe b. 20.0 g of hydrogen gas was reacted with 50.0 g of nitrogen gas to yield ammonia gas (NH3) Calculate TY for NH3 12.For the following reaction: 50.0grams of Fe was reacted in excess oxygen producing 58.0 grams of Fe2O3(s) . Calculate the percent yield. Fe(s) + O2(g) —-> Fe2O3(s) 13. A student performed the following reaction in the lab. Her professor told her she should be able to achieve a minimum of 80.0% yield for her product, ZnO. The student starts with 25.0 grams of zinc sulfide in excess oxygen gas. What is the minimum mass of zinc oxide the reaction needs to produce to achieve an 80.0% yield? ZnS(s) + O2(g) —> ZnO(s) + SO2(g) Excess Reactant 14. For 12a and 12b determine the amount of excess reactant left unreacted, 15. Balance the following chemical reaction. Full Stoichiometry Problem. WILL BE ONE LIKE THIS ON EXAM 1! Fe2O3(s) + CO(g) ——–> Fe(s) + CO2(g) a. Balance the reaction b. Find the limiting reactant if you start with 150.0g of Fe2O3 and 73.50 g of CO. c. Calculate the theoretical yield of Fe in grams. d. Calculate the percent yield if the actual yield was 78.0 grams. e. Calculate the amount of excess reactant that was used during the reaction and how much was left unreacted.
Assignment Answer
Introduction
Stoichiometry is a fundamental concept in chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It plays a crucial role in understanding and predicting the outcome of chemical reactions, as well as in practical applications, such as determining the amount of substances used or produced in a reaction. This paper delves into various aspects of stoichiometry, including calculating molecular weights, moles, grams, and exploring the principles of chemical reactions. The content aims to provide a comprehensive guide for students and enthusiasts in the field of chemistry.
1. Calculating Molecular Weights
1.1 Molecular Weight of Pb(HSO4)2
To calculate the molecular weight of Pb(HSO4)2, we need to consider the atomic weights of each element in the compound. Lead (Pb) has an atomic weight of approximately 207.2 g/mol, hydrogen (H) is approximately 1.01 g/mol, sulfur (S) is approximately 32.07 g/mol, and oxygen (O) is approximately 16.00 g/mol.
The molecular weight of Pb(HSO4)2 can be calculated as follows: Molecular Weight = (2 * Atomic Weight of H) + Atomic Weight of Pb + (2 * Atomic Weight of S) + (8 * Atomic Weight of O)
Now, calculate the molecular weight of Pb(HSO4)2.
1.2 Molecular Weight of Al2(SO4)3
The molecular weight of Al2(SO4)3 can be determined in a similar way. Aluminum (Al) has an atomic weight of approximately 26.98 g/mol, sulfur (S) is approximately 32.07 g/mol, and oxygen (O) is approximately 16.00 g/mol.
The molecular weight of Al2(SO4)3 can be calculated as follows: Molecular Weight = (2 * Atomic Weight of Al) + (3 * Atomic Weight of S) + (12 * Atomic Weight of O)
Calculate the molecular weight of Al2(SO4)3.
2. Calculating Number of Moles
2.1 Moles of Pb(NO3)2
To calculate the number of moles of Pb(NO3)2, you need to know its molecular weight. Lead (Pb) has an atomic weight of approximately 207.2 g/mol, nitrogen (N) is approximately 14.01 g/mol, and oxygen (O) is approximately 16.00 g/mol.
The number of moles can be calculated using the formula: Number of Moles = Mass (g) / Molecular Weight (g/mol)
Calculate the number of moles of Pb(NO3)2 when given 28.4g of the compound.
2.2 Moles of Calcium Chloride (CaCl2)
Calcium (Ca) has an atomic weight of approximately 40.08 g/mol, and chlorine (Cl) is approximately 35.45 g/mol.
Calculate the number of moles of calcium chloride when given 10.0g of the compound.
2.3 Grams from Moles
2.3a Moles of Aluminum Carbonate (Al2(CO3)3)
Aluminum (Al) has an atomic weight of approximately 26.98 g/mol, carbon (C) is approximately 12.01 g/mol, and oxygen (O) is approximately 16.00 g/mol.
Calculate the number of grams when provided with 2.750 moles of aluminum carbonate.
2.3b Moles of Bromine (Br2)
Bromine (Br2) has a molar mass of approximately 159.81 g/mol.
Calculate the number of grams when given 0.0100 moles of bromine.
3. Moles and Atoms/Molecules
3.1 Moles, Molecules, and Atoms in O2
Oxygen (O2) has a molar mass of approximately 32.00 g/mol. You are provided with 8.0g of O2.
Calculate the number of moles, molecules, and the total number of atoms in this sample.
3.2 Moles, Molecules, and Atoms in Magnesium Phosphide (Mg3P2)
Magnesium (Mg) has an atomic weight of approximately 24.31 g/mol, and phosphorus (P) is approximately 30.97 g/mol.
You are given 16.0g of magnesium phosphide. Calculate the number of moles, molecules, the number of magnesium atoms, and the number of phosphorus atoms.
3.3 Total Number of Atoms in a Compound
You are also required to calculate the total number of atoms in a compound based on the given mass. Provide detailed calculations and explanations.
4. Moles and Grams from Atoms and Molecules
4.1 Atoms of Calcium (Ca)
You are given 1.48 x 10^24 atoms of calcium. Calculate the number of moles and the number of grams.
4.2 Molecules of Dinitrogen Tetroxide (N2O4)
You are provided with 6.487 x 10^22 molecules of dinitrogen tetroxide. Calculate the number of moles and the number of grams.
5. Mass Percent Calculation
5.1 Mass Percent of Al2(SO4)3
Calculate the mass percent of each element in Al2(SO4)3.
5.2 Mass Percent of C5H13O4N2
Determine the mass percent of each element in the compound C5H13O4N2.
6. Empirical and Molecular Formulas
6.1 Empirical and Molecular Formula for a Compound
Given the molar mass of 292.52 g/mol and the mass percentages of carbon, oxygen, and hydrogen, determine the empirical and molecular formula for the compound.
6.2 Empirical Formula of Adipic Acid
The composition of adipic acid is provided. Calculate its empirical formula and the molecular formula for a compound with a molar mass of 219.24 g/mol.
7. Balancing and Identifying Types of Reactions
7.1 Balancing and Identifying Reaction Type for Mg + O2
Balance the reaction of magnesium (Mg) with oxygen (O2), and identify the type of reaction.
7.2 Balancing and Identifying Reaction Type for KClO3
Balance the reaction of potassium chlorate (KClO3) and identify the type of reaction.
7.3 Balancing and Identifying Reaction Type for C3H8 + O2
Balance the reaction of propane (C3H8) with oxygen (O2) and identify the type of reaction.
7.4 Balancing and Identifying Reaction Type for H2 + N2
Balance the reaction of hydrogen (H2) and nitrogen (N2) and identify the type of reaction.
8. Mole to Mole Conversions
8.1 Moles of O2 in the Reaction with C2H6
Calculate the number of moles of O2 that react with 6.75 moles of ethane (C2H6) in the provided reaction.
8.2 Moles of O2 Produced by KClO3
Determine how many moles of O2 are produced when 6.75 moles of potassium chlorate (KClO3) react.
9. Theoretical and Percent Yield
9.1 Theoretical Yield of PCl3
Given the reaction between phosphorus (P4) and chlorine (Cl2) and an actual yield of 35.0g of PCl3, calculate the theoretical yield.
9.2 Percent Yield of PCl3
Calculate the percent yield of PCl3 using the theoretical yield and the actual yield.
10. Limiting Reactant and Theoretical Yield
10.1 Limiting Reactant for Fe2O3 + CO
Given 100.0g of iron(III) oxide (Fe2O3) and 50.0g of carbon monoxide (CO) in the reaction, determine the limiting reactant and calculate the theoretical yield.
10.2 Theoretical Yield for NH3
Given 20.0g of hydrogen gas (H2) and 50.0g of nitrogen gas (N2) in the formation of ammonia (NH3), calculate the theoretical yield.
11. Percent Yield Calculation
11.1 Percent Yield for Fe2O3 + O2
Given the actual yield of 58.0g of iron(III) oxide (Fe2O3) and a starting mass of 50.0g of iron (Fe) in a reaction with oxygen (O2), calculate the percent yield.
12. Minimum Mass for Desired Yield
12.1 Minimum Mass of ZnO
Determine the minimum mass of zinc oxide (ZnO) needed to achieve an 80.0% yield when starting with 25.0g of zinc sulfide (ZnS) in a reaction with oxygen (O2).
13. Excess Reactant Calculation
Calculate the amount of excess reactant left unreacted for the given reactions.
14. Balancing the Stoichiometry
14.1 Full Stoichiometry Problem for Fe2O3 + CO
Balancing the reaction of iron(III) oxide (Fe2O3) with carbon monoxide (CO) and determining the limiting reactant, theoretical yield, percent yield, and excess reactant.
This comprehensive guide covers a wide range of stoichiometry topics, including calculations, balancing reactions, and yield calculations. By following the provided information and performing the calculations, you will gain a deeper understanding of stoichiometry in chemistry.
FAQs (Frequently Asked Questions)
1. What is stoichiometry, and why is it important in chemistry?
Stoichiometry is a branch of chemistry that deals with the quantitative relationships in chemical reactions. It is essential for understanding how reactants transform into products and plays a crucial role in various applications, including determining reaction efficiency and substance quantities.
2. How do I calculate the molecular weight of a compound?
The molecular weight of a compound is calculated by summing the atomic weights of all the elements in the compound. You can find the atomic weights in the periodic table. For example, the molecular weight of Pb(HSO4)2 is determined by adding the atomic weights of Pb, H, S, and O.
3. What is the significance of balancing chemical reactions, and how is it done?
Balancing chemical reactions ensures that the number of atoms on the reactant side equals the number of atoms on the product side. This is vital for maintaining the law of conservation of mass. Balancing involves adjusting coefficients in front of chemical formulas to achieve equilibrium.
4. How is the empirical formula of a compound determined using mass percentages?
The empirical formula can be found by determining the mole ratios of different elements based on their mass percentages in the compound. Once you have the mole ratios, you can simplify them to obtain the empirical formula.
5. What is the limiting reactant in a chemical reaction, and why is it important to identify it?
The limiting reactant is the substance that is completely consumed in a chemical reaction, thus limiting the amount of product formed. Identifying the limiting reactant is crucial for determining the maximum amount of product that can be obtained and for avoiding wastage of reactants.
