Determine the number of atoms in a sample of nickel that has a mass of 8.30 × 10−12 g

There are 8.4 × 10¹⁰ atoms in the given sample of Nickel.

Explanation:

To find the number of atoms in the given mass of Nickel, first we have to find the number of moles using its mass and molar mass of nickel then multiply the moles by the Avogadro's number so that we will get the number of atoms in that sample of nickel.

Moles of Nickel =  

                   =

                  = 1.4 × 10⁻¹³ moles

Now we have to multiply the number of moles by Avogadro's number, we will get the number of atoms of Nickel.

Number of atoms = 1.4 × 10⁻¹³× 6.022 × 10²³

                             = 8.4 × 10¹⁰ atoms of Nickel

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2