Question

How many moles are in 4.24kg of Na2CO3?

Hint : You need to convert from kg to grams first
A. 4.00 x 10 -2 moles
B. 40.0 moles
C. 4.49 x 105 moles
D. 2.55 x 1028 moles

Answer 1

Data:
4.24 Kg converting (grams) → 4240 g

Molar Mass of
`Na_(2) CO_(3)`
Na = 2*23 = 46 amu
C = 1*12 = 12 amu
O = 3*16 = 48 amu
-------------------------
Molar Mass of
`Na_(2) CO_(3)` = 46 + 12 + 48 = 106 g/mol

If:

106 g → 1 mol
4240 g → y

Solving: Rule of three (directly proportional)

`(106)/(4240) = (1)/(y)`
multiply cross
106*y = 4240*1
106y = 4240

`y = (4240)/(106)`

`\boxed{\boxed{y = 40\:moles}}\end{array}}\qquad\quad\checkmark`

Answer:
B. 40.0 moles