Question

Sodium reacts with oxygen to produce sodium oxide.4Na(s)+O2(g)→2Na2O(s)1. If you have 16.0 g of Na , how many grams of O2 are required for the reaction?2. How many grams of O2 are needed in a reaction that produces 70.0 g of Na2O ?

Answer 1

In this question, we have the following reaction occurring:

4 Na + O2 -> 2 Na2O

From this balanced reaction, we can determine the following molar ratios:

4 Na = 1 O2

4 Na = 2 Na2O

1 O2 = 2 Na2O

1. In this part, we have 16 grams of Na, now we have to find the number of moles that represents 16 grams, and we can do that by using its molar mass, 23g/mol

23g = 1 mol of Na

16g = x moles of Na

23x = 16

x = 16/23

x = 0.7 moles of Na in 16 grams

According to the molar ratio, if we have 4 moles of Na, we need 1 mol of O2, therefore if we have 0.7 moles of Na:

4 Na = 1 O2

0.7 Na = x O2

4x = 0.7

x = 0.7/4

x = 0.175 moles of O2 are required to react with 0.7 moles of Na

Now that we have the number of moles of O2, we can calculate the mass that is required to react with Na, we have to use its molar mass, 32g/mol

32g = 1 mol

x grams = 0.175 moles

x = 0.175 * 32

x = 5.6 grams of O2 will react with 16 grams of Na

Answer will be 5.6 grams of O2