Question

How many formula units of baking soda (sodium bicarbonate) are in 2.60 tsp? (1 tsp ≈ 7.20 g nahco3)?

Answer 1

2.60 x 7.20= 18.72 g NaHCO3

Answer 2

In 1 mole of
`NaHCO_(3)` there are
`6.023* 10^(23)` formula units of
`NaHCO_(3)`.

Since, 1 tsp of
`NaHCO_(3)` is approximately 7.20 g of
`NaHCO_(3)`. Mass of 2.60 tsp of
`NaHCO_(3)` can be calculated as follows:

`1 tsp\rightarrow 7.20 g`

Thus,

`2.60 tsp\rightarrow (2.60)(7.20 g)=18.72 g`

Converting mass into number of moles as follows:

`n=(m)/(M)`

here, n is number of moles, m is mass and M is molar mass.

Molar mass of
`NaHCO_(3)` is 84 g/mol thus, number of moles will be:

`n=(18.72 g)/(84 g/mol)=0.22 mol`

Since,
`1 mole\rightarrow 6.023* 10^(23)formula units`

thus,

`0.22 mol\rightarrow 6.023* 10^(23)* 0.22=1.34* 10^(23)formula units`

Thus,
`1.34* 10^(23)` formula units of baking soda are in 2.60 tsp.