# What is the molar mass (gram formula mass) for the compound sodium thiosulfate, Na_2S_2O_3?

Mar 15, 2018

I get $158.13 \setminus \text{g/mol}$.

#### Explanation:

To calculate the molar mass of sodium thiosulfate, $N {a}_{2} {S}_{2} {O}_{3}$, we need to find all the molar masses of the elements, and add them together.

$N a$ has a molar mass of $23 \setminus \text{g/mol}$. So, $N {a}_{2}$ will have a molar mass of $23 \setminus \text{g/mol"*2=46 \ "g/mol}$.

$S$ has a molar mass of $32.065 \setminus \text{g/mol}$. So, ${S}_{2}$ will have a molar mass of $32.065 \setminus \text{g/mol"*2=64.13 \ "g/mol}$.

$O$ has a molar mass of $16 \setminus \text{g/mol}$. Therefore, ozone, or ${O}_{3}$, will have a molar mass of $16 \setminus \text{g/mol"*3=48 \ "g/mol}$.

Adding all the molar mass together, we find that the molar mass of sodium thiosulfate $\left(N {a}_{2} {S}_{2} {O}_{3}\right)$ is:

$46 \setminus \text{g/mol"+64.13 \ "g/mol"+48 \ "g/mol}$

$= 158.13 \setminus \text{g/mol}$.