Molar Ratio Lesson

Review of PS1-7

Current Standard

HS-PS1-7:

​Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.

Learning Targets

PS1-​7.1: I can describe the relationships between molar ratios using particle diagrams and chemical equations.

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​PS1-7.2: I can calculate molar mass of reactants and products to prove mass is conserved in a chemical reaction.

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​PS1-7.3:I can use stoichiometry to prove the mass, atoms, and moles are conserved.

Multiple Choice

1. What is the molar ratio of KOH to K3PO4 in the following reaction:

$$Na_3PO_4+3\ KOH→K_3PO_4+3\ NaOH$$

• 1 mol KOH : 1 mol K3PO4

• 1 mol K3PO4 : 3 mol KOH

• 3 mol KOH : 1 mol K3PO4

• 1 mol Na3PO4 : 1 mol K3PO4

Open Ended

2. What is the molar ration of C3H6O to CO2 in the following reaction: $$2\ C_3H_6O+8\ O_2→6\ CO_2+6\ H_2O$$  

Multiple Choice

3. If 6 moles of CO2 were used in the chemical reaction, how many moles of oxygen were used? $$C_3H_8+5\ O_2→3\ CO_2+4\ H_2O$$  

• 6 moles O2

• 5 moles O2

• 10 moles O2

• 8 moles O2

​4. Drawing Molar Ratios

Open Ended

5. What is so special about the molar mass of an element?

Multiple Choice

6. What is the mass of one mole of Rhodium?

• 45 g/mol

• 103 g/mol

• 86 g/mol

• 6.02 x 10^23 g/mol

Open Ended

7. What is the molar mass of Mn2Se7?

Multiple Choice

8. What is the molar mass of AuCl3?

• 303 g/mol

• 233 g/mol

• 96 g/mol

• 130 g/mol

Open Ended

9. How many moles of epsom salt (MgSO4) are in 720 grams?

Open Ended

10. How many moles are in 89 grams of copper (II) hydroxide, Cu(OH)2?

Multiple Choice

11. This reaction started with 85 grams of P4, and ended with 209g of P2O5. How much oxygen was needed to react with the phosphorus?

$$P_4+5\ O_2→2\ P_2O_5$$  

• 85 grams

• Not enough information

• 209 grams

• 124 grams

Open Ended

12. 136 grams of Cr2O3 and 54 grams of Mg react together to make 101 grams of Cr, how much MgO is produced?

$$Cr_2O_3+3\ Mg→2\ Cr+3\ MgO$$  

Open Ended

13. Using stoichiometry, how much H2O is produced from 74g of NaOH? $$2\ NaOH+H_2SO_4→2\ H_2O+Na_2SO_4$$  

Open Ended

 14. Using stoichiometry, how many grams of H2O are produced from 318g of Al(OH)3?

$$3\ HBr+Al(OH)_3→3\ H_2O+AlBr_3$$  

Open Ended

15. Is the following combustion reaction balanced? Use a table to prove your answer. $$C_6H_{12}+9\ O_2→6\ CO_2+6\ H_2O$$  

Multiple Choice

16. How many particles are in 47g of pure iodine, I2?

• 6.02 x 10^23

• 1.11 x 10^23

• 1.11 x 10^24

• 94

Open Ended

Look back at the learning targets at the top of your worksheet. What do you struggle with the most in this unit? What can we do in class to help you understand that part better?