How may moles are in 145.54 g of SIO2

The number of mole is 2.422 moles

Explanation:

To calculate the number of mole, we have to use the formula n = m /Mm

n - moles

m - mass

Mm - molar mass

Let's calculate the molar mass of the compound SiO2

Si - 28.0855

O - 15.999

Note: there are two atoms of oxygen in the compound

Mm of SiO2= 28.0855+ 2* 15.999

= 60.0835g/mol

Now, we calculate the number of moles

n = 145.54g/ 60.0835g/mol

= 2.422mol

a

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o