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

how many moles of potassium sulfide are in a 65.50g sample?

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  =

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

              Number of moles  =   = 0.59moles

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.