Question

If I have 150g of NaNO3, how many moles are there?

a) 1.76 mol NaNO3
b) 12750 mol NaNO3
c) 17.6 g NaNO3
d) 0.56 mol NaNO

Answer 1

`\boxed {\boxed {\sf A.\ 1.76 \ mol \ NaNO_3}}`

Step-by-step explanation:

To covert from grams to moles, the molar mass is used. This is the mass of 1 mole of a substance. These are located on the Periodic Table. They are the equivalent to the atomic masses, but have different units: grams per mole.

We are given the compound: NaNO₃

Look up the values for each individual element (sodium, nitrogen, and oxygen)

• Na: 22.989769 g/mol
• N: 14.007 g/mol
• O: 15.999 g/mol

Now find the molar mass of the entire compound. Notice that oxygen has a subscript of 3 in the formula, so there are 3 atoms of oxygen per molecule. We must multiply its molar mass by 3 before adding the others.

• O₃: 15.999*3=47.997 g/mol
• NaNO₃: 22.989769+14.007+47.997=84.993769 g/mol

Use this value as a ratio.

`\frac {84.993769 \ g \ NaNO_3}{1 \ mol \ NaNO_3}`

Multiply by the given number of grams: 150

`150 \ g \ NaNO_3*\frac {84.993769 \ g \ NaNO_3}{1 \ mol \ NaNO_3}`

Flip the ratio so the grams of sodium nitrate cancel.

`150 \ g \ NaNO_3*\frac {1 \ mol \ NaNO_3}{84.993769 \ g \ NaNO_3}`

`150 *\frac {1 \ mol \ NaNO_3}{84.993769}`

`\frac {150}{84.993769} \ \ mol \ NaNO_3`

`1.7648352551 \ mol \ NaNO_3`

If we round to the nearest hundredth, the 4 in the thousandth place tells us to leave the 6.

`1.76 \ mol \ NaNO_3`

150 grams of sodium nitrate is approximately 1.76 moles of sodium nitrate. Therefore, choice A is correct.