What mass of O2 is required to produce 14.5g of CO2 if the reaction has a 65.0% yield?

Question

CH4+2 O2 --->CO2 +2 H2O

A) 21.1g
B)32.4g
C)13.7g
D)5.27g
E)16.2g
Can anyone show me how itz done?

Answer 1

Step 1: Determine how many moles of O2 are required to get 1 mole of CO2.

Since there's 2 O2 -> 1 CO2, you need 2 moles O2 per mole CO2.

Step 2: Find how many moles of CO2 are being made.
You have 14.5 g CO2. The molar mass of CO2 is 44g/mol (12 from C, 2* 16 from O). Thus, you have 14.5 / 44 moles = 0.3295 moles of CO2.

Step 3: Find how many moles of O2 you need:
First: Since there is a 65% yield, you need to divide the number of moles of CO2 by 65% to find how many you would have made in a 100% yield reaction: .3295 / .65 = 0.5070 moles CO2.
Second: to make 0.5070 moles of CO2, you need 1.014 moles of O2.

Step 4: Convert moles of O2 to grams.
O2 has a molar mass of 32g/mol (2 * 16). Multiply 1.014 * 32 = 32.4 g. (solution!)