Question 5 A A 5.0 g sample of MgCl, may contain measurable amounts of other compounds as impurities. Which of the following quantities is (are) needed to determine that the sample is pure MgCl,?
The color and density of the sample
The mass of Mg in the sample only
The number of moles of Cl in the sample only
The mass of Mg and the mass of Cl in the sample

C3H8 + 502+3CO2 + 4H20

Explanation:

In order to get this answer you would have to would balance out the carbons on the products side by multiplying CO2 by 3. The new equation will be 

C3H8 + 02 > 3CO2 + H20

Now, that the carbons are balanced, we will look at the hydrogens. We can multiply the number of waters on the product side by 4, to make 4 H20 molecules. This gives both sides of the equation 8 hydrogens. Next we can check our oxygens. There will be 10 oxygens on the products side and 2 on the reactants so to balance these out, we multiply the 02 on the reactants side by 5.