# Natasha's mother gave her a solid gold necklace. She determines the chain has a mass of 7.6 g. The density of pure gold is 19.3 g/cm^3. About how much gold was used to make her necklace?

Aug 8, 2016

${\text{0.39 cm}}^{3}$

#### Explanation:

Assuming that the neckless is made from $\text{24K}$, $24$ karat gold, i. e. gold that is 99.9% pure, you can solve this problem by using the mass of the neckless and the density of pure gold.

You know that gold has a density of ${\text{19.3 g cm}}^{- 3}$. This tells you that every milliliter of gold has a mass of $\text{19.3 g}$. In your case, the mass of gold is said to be equal to $\text{7.6 g}$.

This means that in order to get this mass of gold, you must use

7.6 color(red)(cancel(color(black)("g"))) * overbrace("1 cm"^3/(19.3 color(red)(cancel(color(black)("g")))))^(color(blue)("the density of gold")) = color(green)(|bar(ul(color(white)(a/a)color(black)("0.39 cm"^3)color(white)(a/a)|)))

The answer is rounded to two sig figs, the number of sig figs you have for the mass of the neckless.