Question

How many grams of potassium chloride must decompose to produce 69.9 milliliters of potassium metal, if the density of potassium is 1.78 g/mL? Show all steps of your calculation as well as the final answer.

Answer 1

2KCl = 2K + Cl₂

v(K)=69.9 ml
p(K)=1.78 g/ml
M(K)=39.1 g/mol
M(KCl)=74.6 g/mol

1) m(K)=v(K)p(K)

2) m(KCl)=M(KCl)m(K)/M(K)

3) m(KCl)=M(KCl)v(K)p(K)/M(K)

m(KCl)=74.6*69.9*1.78/39.1=237.39 g

Answer 2

Explanation:

It is known that density is mass divided by volume of a substance.

Mathematically,        Density = $\frac{mass}{volume}$

Since, it is given that volume is 69.9 mL and density is 1.78 g/mL.

Hence, calculate the mass as follows.

            Density = $\frac{mass}{volume}$

               1.78 g/mL = $\frac{mass}{69.9 mL}$

                 mass = 124.42 g

Thus, we can conclude that mass of potassium chloride is 124.42 g.