Question

what quantity in atoms of silicon are produced by the complete reaction of 8.69 grams of carbon with excess quartz (sio₂), according to the balanced chemical reaction sio₂(s) + 2 c(s) → si(s) + 2 co(g)

Explanation:

Step1: Calculate moles of carbon

Given mass of carbon \(m = 8.0g\), molar mass of carbon \(M = 12.01g/mol\).
Using the formula \(n=\frac{m}{M}\), we have \(n_{C}=\frac{8.0g}{12.01g/mol}\approx0.666mol\).

Step2: Use mole - ratio from the balanced equation

From the balanced equation \(SiO_{2}(s)+2C(s)\to Si(s)+2CO(g)\), the mole ratio of \(C\) to \(Si\) is \(2:1\).
Let \(n_{Si}\) be the moles of silicon. Using the ratio \(\frac{n_{C}}{n_{Si}}=\frac{2}{1}\), then \(n_{Si}=\frac{n_{C}}{2}\).
Substituting \(n_{C} = 0.666mol\), we get \(n_{Si}=\frac{0.666mol}{2}=0.333mol\).

Answer:

\(0.33mol\) (rounded to two significant figures)