Question

How many moles are in (1) 8g of helium (2)78g of zinc (3)11.2 of oxygen gas at s.t.p.

Answer 1

2moles

1.20moles

0.5mole

Explanation:

Given parameters:

Mass of He = 8g

Mass of Zn = 78g $\frac{78}{65.4}$

Volume of oxygen gas= 11.2L

Unknown:

Number of moles of He, Zn = ?

Number of moles of oxygen gas = ?

Solution;

Number of moles of substances is given as :

 Number of moles = $\frac{mass}{molar mass}$

 molar mass of He = 4g/mol

  molar mass of Zn = 65.4g/mol

Number of moles of He = $\frac{8}{4}$  = 2moles

Number of moles of Zn =  $\frac{78}{65.4} =$ 1.20moles

For gases at STP;

 Number of moles = $\frac{volume of gas}{22.4}$

   Number of moles = $\frac{11.2}{22.4}$  = 0.5mole

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Number of moles brainly.com/question/1841136

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