Question

1. 76g 2ag₂o → 48g 4ag + ____o₂
2. ____s₈ + 107g 12o₂ → 352g 8so₃
3. 123g 6co₂ + ____6h₂o → 543g c₆h₁₂o₆ + 313g o₂
4. 117g 2k + ____mgbr₂ → 195g 2kbr + 203g mg
5. 506g 2hcl + 45g caco₃ → 109g cacl₂ + ____h₂o + 312g co₂
6. 413g hno₃ + 87g nahco₃ → 105g nano₃ + 217g h₂o + ____co₂
7. ____sn(oh)₂ + 813g 2hbr → 671g 2h₂o + 546g snbr₂
8. 787g 2gaf₃ + 463g 3na₂so₃ → ____6naf + 547g ga₂(so₃)₃
9. 67g c₂h₄ + 23g 3o₂ → 44g 2co₂ + ____2h₂o
10. 94g fecl₂ + ____2koh → 57g fe(oh)₂ + 73g 2kcl
11. ____li + 106g h₂o → 48g 2lioh + 212g h₂
12. 149g 2na + ____caf₂ → 400g 2naf + 87g ca
13. ____2hcl + 98g ca(hco₃)₂ → 66g cacl₂ + 41g 2h₂o + 87g 2co₂
14. 172g 2hno₂ + 263g na₂co₃ → ____2nano₂ + 83g h₂o + 111g co₂

Explanation:

These problems use the Law of Conservation of Mass: total mass of reactants = total mass of products. For each, calculate the unknown mass by rearranging this relationship.

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Problem 13

Step1: Sum reactant masses

$76\ \text{g}$

Step2: Sum known product masses

$48\ \text{g}$

Step3: Solve for unknown $\text{O}_2$

$76 - 48 = 28\ \text{g}$

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Problem 14

Step1: Sum product masses

$352\ \text{g}$

Step2: Sum known reactant masses

$107\ \text{g}$

Step3: Solve for unknown $\text{S}_8$

$352 - 107 = 245\ \text{g}$

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Problem 15

Step1: Sum product masses

$541 + 313 = 854\ \text{g}$

Step2: Sum known reactant masses

$123\ \text{g}$

Step3: Solve for unknown $6\text{H}_2\text{O}$

$854 - 123 = 731\ \text{g}$

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Problem 16

Step1: Sum product masses

$195 + 203 = 398\ \text{g}$

Step2: Sum known reactant masses

$117\ \text{g}$

Step3: Solve for unknown $\text{MgBr}_2$

$398 - 117 = 281\ \text{g}$

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Problem 17

Step1: Sum reactant masses

$506 + 45 = 551\ \text{g}$

Step2: Sum known product masses

$109 + 312 = 421\ \text{g}$

Step3: Solve for unknown $\text{H}_2\text{O}$

$551 - 421 = 130\ \text{g}$

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Problem 18

Step1: Sum reactant masses

$413 + 87 = 500\ \text{g}$

Step2: Sum known product masses

$105 + 217 = 322\ \text{g}$

Step3: Solve for unknown $\text{CO}_2$

$500 - 322 = 178\ \text{g}$

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Problem 19

Step1: Sum product masses

$671 + 546 = 1217\ \text{g}$

Step2: Sum known reactant masses

$813\ \text{g}$

Step3: Solve for unknown $\text{Sn(OH)}_2$

$1217 - 813 = 404\ \text{g}$

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Problem 20

Step1: Sum reactant masses

$787 + 463 = 1250\ \text{g}$

Step2: Sum known product masses

$547\ \text{g}$

Step3: Solve for unknown $6\text{NaF}$

$1250 - 547 = 703\ \text{g}$

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Problem 21

Step1: Sum reactant masses

$67 + 23 = 90\ \text{g}$

Step2: Sum known product masses

$44\ \text{g}$

Step3: Solve for unknown $2\text{H}_2\text{O}$

$90 - 44 = 46\ \text{g}$

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Problem 22

Step1: Sum product masses

$57 + 73 = 130\ \text{g}$

Step2: Sum known reactant masses

$94\ \text{g}$

Step3: Solve for unknown $2\text{KOH}$

$130 - 94 = 36\ \text{g}$

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Problem 23

Step1: Sum product masses

$48 + 212 = 260\ \text{g}$

Step2: Sum known reactant masses

$106\ \text{g}$

Step3: Solve for unknown $\text{Li}$

$260 - 106 = 154\ \text{g}$

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Problem 24

Step1: Sum product masses

$400 + 87 = 487\ \text{g}$

Step2: Sum known reactant masses

$149\ \text{g}$

Step3: Solve for unknown $\text{CaF}_2$

$487 - 149 = 338\ \text{g}$

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Problem 25

Step1: Sum product masses

$66 + 41 + 87 = 194\ \text{g}$

Step2: Sum known reactant masses

$98\ \text{g}$

Step3: Solve for unknown $2\text{HCl}$

$194 - 98 = 96\ \text{g}$

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Problem 26

Step1: Sum reactant masses

$172 + 263 = 435\ \text{g}$

Step2: Sum known product masses

$83 + 111 = 194\ \text{g}$

Step3: Solve for unknown $2\text{NaNO}_2$

$435 - 194 = 241\ \text{g}$

Answer:

1. $28\ \text{g}$
2. $245\ \text{g}$
3. $731\ \text{g}$
4. $281\ \text{g}$
5. $130\ \text{g}$
6. $178\ \text{g}$
7. $404\ \text{g}$
8. $703\ \text{g}$
9. $46\ \text{g}$
10. $36\ \text{g}$
11. $154\ \text{g}$
12. $338\ \text{g}$
13. $96\ \text{g}$
14. $241\ \text{g}$