question 1
by use of Avogadro law
that is,1 mole = 6.02 x10^23 atoms
what about 0.60 moles
by use of cross multipication
=(0.60 mole/ x 6.02 x10^23)/ 1mole = 3.612 x10^23 atoms of Zn
question 2
by use of Avogadro law constant
that is 1 mole =6.02 x10^23 molecules
what about 3.52 x10^24 molecules
by cross multiplication
=( 1 mole x3.52 x10^24 molecules/6.02 x10^23 molecules) = 5.847 moles of water
question 3
by use of Avogadro law constant
1 mole = 6.02 x10^23 atoms
what about 2 moles =? atoms
by use of cross multiplication
=( 2moles x 6.02 x10^23 )/1mole= 1.204 x10^24 atoms of Li
question 4
by use of Avogadro law constant
1 mole = 6.02 x10^23 atoms
what about 6.02 x10^23 atoms =? moles
cross multiplication
(1 mole x6.02 x10^23 atoms)/(6.02 x10^23 atoms)= 1 mole of carbon
question 5
by use Avogadro law constant
1 mole =6.02 x10^23 molecules
what about 4.9 x10^23 moles =? moles
by cross multipication
=( 1mole x 4.9 x10^23 molecules) /6.02 x10^23 molecules = 0.81 moles ZNCl2
You missed a lot of details in your question, so when we have the complete question as the attached picture so, the answer would be:
when we have the value of Ka = 1.8 x 10^-5 so, we can use it to get the Pka value
by using this formula:
Pka = -㏒Ka
= -㏒(1.8 x 10^-5)
= 4.7
now, after we have got the Pka we need now to get moles of NaC2H3O2 and
moles of HC2H3O2:
when moles of NaOH = 0.015 moles
when moles NaC2H3O2 after adding NaOH
= initial mol NaC2H3O2 + mol NaOH
∴moles NaC2H3O2 = 0.1 + 0.015 = 0.115 moles
and moles HC2H3O2 after adding NaOH
= initial mol HC2H3O2 - mol NaOH
∴ moles HC2H3O2 = 0.1 - 0.015 = 0.085 moles
so, when we have moles [HC2H3O2] &[NaC2H3O2] so we can substitution its values in [A] &[HA] :
by using H-H equation we can get the PH:
when PH = Pka + ㏒[A]/[HA] PH = 4.7 + ㏒0.115/0.085
= 4.8
Answer: 3.29 × 1023 atoms