If 23 grams of sodium are used, how many grams of O2 are needed and how many grams of Na2O are formed?

Question

Chemistry questions 4Na+2O2>>>>2Na2O

Answer 1

So the reaction you wrote has a small typo. I believe it should be 4Na + O₂ → 2Na₂O. From the way you stated the question, you want to know how many grams of O₂ are needed to fully react with 23 g of Na and how many grams of product form. To figure this out, you need to know that a mole of O₂ weighs 32g, and convert 23 g Na to moles of Na using a periodic table. 

 

23g Na*(1/22.99 g mol^-1) = 1 mol Na. 

 

1 mol Na*(1 mol O₂/4 mol of Na)*(32 g O₂/mol O₂)= 8 g O₂

 

So you need 8g O₂ to fully combust 23g Na. You have a total mass on the reactants side of 31g, and the law of conservation of mass tells you that you form (in a perfect world) 31g of Na₂O.