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## Chemistry - Stoichiometry Test Review

**2. Solid Sodium and chlorine gas react to produce solid sodium chloride:**

## 2Na + Cl2 = 2NaCl

**a. How many moles of chlorine gas (Cl2) would react with 5.0 moles of sodium (Na)?**

**Solution: **

2(a)
| **Na** | **Cl2** |

*Per Equation or Theoretically*
| *2 moles* | *1 mole* |

*Actual* | 5 moles | x mole? |

****

2/5 = 1/x; 2x = 5; x = 2.5 moles, Answer.

**b. Determine the mass of NaCl that can be produced from 24.7 g Na.**

Solution:

2(b) | **Na** | **NaCl** |

*Per Equation or Theoretically* | 2 x 22.99 = 45.98 g | 2 x (22.99 + 35.45)g = 116.88 g |

*Actual* | *24.7 g* | *x?* |

45.98/24.7 = 116.88/x; x = 62.8 g, Answer

***c*. How many molecules of Cl2 would be needed to react with 24.7 g Na?

**Solution:**

2(c) | Na | Cl2 |

*Per Equation or theoretically* | 45.98 g | 6.02 x 10^23 molecules |

*Actual* | 24.7 g | x? |

****

45.98/24.7 = 6.02 x 10^23 / x; x = 3.24 x 10^23 molecules, Answer

3.

## 2C8H18 + 25O2 = 16CO2 + 18H2O

**a. If 27.3 g of C8H18 are burned, what mass of water will be produced?**

**Solution:**

| **C8H18** | **H2O** |

*Per Equation or theoretically*
| 2x(8x12 +18x1)
= 228 g | 18x(2+16)
=324 g |

*Actual*
| 27.3 g | x? |

228/27.3 = 324/x; x = 324x27.3/228 = 38.7 g of H2O, Answer

**b. How many molecules of CO2 will be produced, using the same given quantity from part a?**

**Solution:**

| **C8H18**
| **CO2** |

Per Equation or theoretically
| 228 g | 16 x 6.02 x 10^23 molecules |

Actual
| 27.3 g | x? |

228/27.3 = 16x6.02x10^23/x; x = 1.15 x 10^24 molecules of CO2, Answer

**c. What volume of CO2 gas is produced, using the same quantity from part a (at STP)?**

**Solution:**

| **C8H18** | **CO2** |

Per Equation or theoretically
| 228 g | 16 x 22.4 L |

Actual
| 27.3 g | x? |

228/27.3 = 16x22.4/x; x = 42.9 L of CO2, Answer