Question

How many liters of a 2.00 M NaOH solution are needed for a reaction that requires 3.55g of NaOH?

Answer 1

Answer:

5 litres of solution are requried

Explanation:

Given that the typical units of

concentration

are

m

o

l

⋅

L

−

1

, to get

concentration

or

amount of moles

or

volume of solution

we just have to take the appropriate product or quotient.

We want

1.0

⋅

m

o

l

N

a

O

H

:

this the product

Volume of solution

×

Concentration

.

So we need the quotient:

Moles of solute

Concentration

=

1.0

⋅

m

o

l

0.2

⋅

m

o

l

⋅

L

−

1

=

5

⋅

L

.

(i.e.

1

1

⋅

L

−

1

=

1

⋅

L

)

Note that we go to such trouble in including the units in these calculations as an extra check on our arithmetic. Sometimes you ask yourself should I divide or should I multiply. Dimensional analysis answers our question. We wanted an answer in

litres

, and we got one. This persuades us that we did the calculation right.