Question

How many hydrogen atoms are in 78.4 grams of hydrochloric acid

Answer 1

You should get about 78.4 g H. Convert grams of HCl to moles of HCl by finding total atomic mass of HCl. From there, convert mole of HCl to moles of H which is 1. Last, convert moles of H to g H which is 1g and you should get your answer. Don't forget significant figures. Since you are given 3 in your given information, your answer should have 3 significant figures.

Answer 2

Answer:
`12.95* 10^(23)`

Explanation:

`Moles=\frac{\text{Given mass}}{\text{Molar mass}}`

`{\text {Moles of HCl}=(78.4g)/(36.5g/mol)=2.15`

According to Avogadro's law, 1 mole of every substance contains Avogadro's number of particles.

1 mole of HCl contains=
`6.023* 10^(23)` atoms of Hydrogen

2.15 moles of HCl contains=
`(6.023* 10^(23))/(1)* 2.15=12.95* 10^(23)` atoms of hydrogen.