Question

true/false. write t if the statement is true and f if the statement is false.

1. global warming is due to the greenhouse gases preventing heat from earth escaping into space
2. the primary source for the rising carbon dioxide levels is respiration of the earths growing population.
3. given the recipe: 2 cups flour + 1 egg + 3 oz blueberries - 4 muffins. you can make 9 muffins from 3.5 cups of flour.
4. given the reaction: 2 na(s) + cl₂(g) - 2 nacl(s) the conversion factor for chlorine gas to sodium metal is: 2 mol cl = 2 mol na
5. before determining conversion factors, it is necessary to make sure the equation is properly balanced.
6. the conversion factor for moles of carbon dioxide to mass of carbon dioxide is: 1 mole co₂ = 44.01 g
7. the theoretical yield is the amount of each reactant needed in order to make the maximum amount of product.
8. the actual yield is the amount of product actually produced by a chemical reaction.
9. given the recipe: 2 cups flour + 1 egg + 3 oz blueberries - 4 muffins. if you have 5 cups of flour, 3 eggs and plenty of blueberries, the limiting reagent is the eggs.
10. the actual yield is the same as the theoretical yield if the reaction goes to completion.
11. for the following reaction you have 8 grams of hydrogen and 2 grams of oxygen. 2h₂ + o₂ - 2h₂o the limiting reagent is the oxygen.
12. for the following reaction you have 8 grams of hydrogen and 2 grams of oxygen. 2h₂ + o₂ - 2h₂o the excess reagent is the oxygen.

Explanation:

1)

Global warming occurs because greenhouse gases (like \(CO_2\)) trap heat (prevent heat from escaping). So the statement is true.

2)

The primary source of rising \(CO_2\) is burning fossil fuels (not respiration of the population). Respiration is a natural cycle. So the statement is false.

3)

From the recipe, 2 cups flour make 4 muffins. So 1 cup flour makes \(4\div2 = 2\) muffins. 3.5 cups flour make \(3.5\times2=7\) muffins (not 9). So the statement is false.

4)

From the reaction \(2Na(s)+Cl_2(g)\to2NaCl(s)\), the mole ratio of \(Cl_2\) to \(Na\) is \(1:2\) (not \(2:2\)). So the statement is false.

5)

Conversion factors are based on stoichiometry (from balanced equations). So the statement is true.

6)

Molar mass of \(CO_2\) (\(C = 12.01g/mol\), \(O = 16g/mol\), \(CO_2=12.01 + 2\times16=44.01g/mol\)). So 1 mole \(CO_2 = 44.01g\). The statement is true.

7)

Theoretical yield is the maximum amount of product (not reactant amount). So the statement is false.

8)

Actual yield is what is actually produced. So the statement is true.

9)

From recipe, 2 cups flour need 1 egg. 5 cups flour need \(5\div2 = 2.5\) eggs (3 eggs are more than enough). So flour is limiting (not eggs). So the statement is false.

10)

If reaction goes to completion (no side - reactions, perfect conditions), actual = theoretical. So the statement is true.

11)

Molar mass \(H_2=2g/mol\), \(O_2 = 32g/mol\). Moles of \(H_2=\frac{8}{2}=4mol\), moles of \(O_2=\frac{2}{32}=0.0625mol\). From \(2H_2+O_2\to2H_2O\), \(O_2\) is limiting. So the statement is true.

12)

Since \(O_2\) is limiting (from 11), \(H_2\) is excess (not \(O_2\)). So the statement is false.

Answer:

1. T
2. F
3. F
4. F
5. T
6. T
7. F
8. T
9. F
10. T
11. T
12. F