Question

What is the mass sample of 0.0500 moles of zinc chloride ?

Answer 1

Answer:

6.82g

0.59moles

Explanation:

1. What is the mass sample of 0.0500 moles of zinc chloride ?

Given parameters:

Number of moles ZnCl₂ = 0.05moles

Unknown:

Mass of the sample  =  ?

Solution:

To find the mass of a substance using the number of moles, it would be pertinent to understand what mole is.

A mole is a substance that contains the avogadro's number of particles.

It relates to the mass using the expression below;

                Mass of a substance  = number of moles x molar mass

Molar mass of  ZnCl₂;

        Atomic mass of Zn  = 65.4g/mol

                                   Cl = 35.5g/mol

Molar mass = 65.4 + 2(35.5)  = 136.4g/mole

Mass of a substance  = 0.05 x 136.4  = 6.82g

2. How many moles of potassium sulfide are in a 65.50g sample?

Given parameters:

Mass of K₂S  = 65.5g

Unknown:

Number of moles  = ?

Solution:

The number of moles of any substance is related to mass using the expression below;

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

Molar mass of K₂S  = 2(39) + 32  = 110g/mol

              Number of moles  = $\frac{65.5}{110}$   = 0.59moles