he molar mass of oxygen gas (O2) is 32.00 g/mol. The molar mass of C3H8 is 44.1 g/mol. What mass of O2, in grams, is required to completely react with 0.025 g C3H8?
0.018
0.034
0.045
0.091

Question

he molar mass of oxygen gas (O2) is 32.00 g/mol. The molar mass of C3H8 is 44.1 g/mol. What mass of O2, in grams, is required to completely react with 0.025 g C3H8?
0.018
0.034
0.045
0.091

perl · Answer

first make a balanced equation

danjs · Answer

Welcome to open study!

perl · Answer

C3H8 + 5 O2 => 3 CO2 + 4 H2O

perl · Answer

now we can make a stoichiometry conversion equation

0.025 g C3H8 * (1 mol C3H8 / 44.1 g C3H8) * ( 5 mol O2 / 1 mol C3H8) * (32 g O2 / 1 mol O2)  = # grams of O2  needed

danjs · Answer

|dw:1419635916635:dw|

danjs · Answer

given, grams to mol conversion, mole ratio to O2, moles to grams of O2. 

Just multiplying by ratios of 1, so that units cancel in your favor.

perl · Answer

By the way I found this really nifty balance equation calculator. you can also use it to find molar mass of say O2 just type O2 = O2 http://www.webqc.org/balance.php

perl · Answer

also there is the famous 
www.ptable.com  for the periodic table stuff