Answer:
0.677 moles
Explanation:
Take the atomic mass of K = 39.1, O =16.0, P = 31.0
no. of moles = mass / molar mass
no. of moles of K3PO4 used = 4.79 / (39.1x3 + 31 + 16x4)
= 0.02256 mol
From the equation, the mole ratio of KOH : K3PO4 = 3 :1,
meaning every 3 moles of KOH used, produces 1 mole of K3PO4.
So, using this ratio, let the no. of moles of KOH required to be y.

y = 0.02256 x3
y = 0.0677 mol
If you don't find exactly 0.677 moles as one of the options, go for the closest one. A very slight error may occur because of taking different significant figures of atomic masses when calculating.
Answer:
= 13.0 moles O2
Explanation:
1] Given the equation: 2C8H18 + 25 O2 ----> 16CO2 + 18H2O
a. How many moles of oxygen gas are required to make 8.33 moles of carbon dioxide?
8.33 moles CO2 X
25mol O2
16mol CO2
= 13.0 moles O2
First, you need to know 1 kg = 10^3 g. And 1 m^3 = 10^6 m^3. So the 1 g/cm3 = 10^3 kg/m3. So the answer is 1.93*10^4 kg/m3.