Question

This reaction shows the complete combustion of octane, C8H18, a component of gasoline....?

2 C8H18(l) + 25 O2(g) 16 CO2(g) + 18 H2O(l)

(a) How many moles of O2 are needed to burn 2.10 mol of C8H18?
(b) How many grams of NaF form when 0.800 mol of HF reacts in this way?
(c) How many grams of Na2SiO3 can be dissolved by 0.600 g of HF?

Answer 1

We use the equation...

`C_8H_18(l) + 25/2O_2(g) rarr8CO_2(g) + 9H_2O(l)+Delta`

Explanation:

I halved your equation in that I find it is easier to determine stoichiometric equivalence in this form rather than the given form.

And so if we burn `2.1*mol` of octane, we need `2.1xx25/2*mol=26.25*mol` with respect to dioxygen...and certainly we could also calculate an equivalent mass, and ALSO an equivalent volume, given a specified pressure.

I will let you address the other questions...they refer to...

`HF(aq) + NaOH(aq) rarr NaF(aq) + H_2O(aq)`

And...

`Na_2SiO_3(aq) + 8HF(aq) rarrH_2SiF_6(aq) +2NaF(aq)+3H_2O(l)`