
Robert S. answered 05/03/21
Dr Bob Loves Science (especially chemistry and math)
Hello, Ethan,
1.) For the reaction C + 2H2 → CH4, how many grams of hydrogen are required to produce 17 moles of methane, CH4 ?
The balanced equation tells us that it takes 2 moles of H2 to make 1 mole of CH4. That's a molar ratio of (2 hyrogen/1 methane) . Since we want 17 moles of methane, we'll need twice that number of moles of hydrogen, 34 moles. Multiply 34 moles H2 time the molar mass of H2 (2 grams/mole) to find that it will take 68 grams of hydrogen to produce 17 moles of methane.
2.) 3 Cu + 8HNO3 → 3 Cu(NO3)2 + 2 NO + 4 H2O
In the above equation, how many grams of water can be made when 1.4 moles of HNO3 are consumed?
Using the same logic, we see that the molar ratio of HNO3,nitric acid, to water is 8/4. We make 4 moles of water for every 8 moles of nitric acid. So we should multiply the moles nitric acid by (1/2) to get moles H2O. That means we only get 0.7 moles of water. Whoopee. Multiply moles water by it's molar mass to arrive at a water mass of 12.6 grams.
Bob