If 35 grams of strontium hydroxide can dissolve in 100 g of water, how much can dissolve in 150 g of water? 0.23 g 4.3 g 23 g 53 g

53 g

Explanation:

35g/100g

We needed to times 1.5 on 100 so we could match 150g of water. That means you'd have to multiply 1.5 on 35g which gives you roughly 53g.

The problem with this question is that you can't really have an aqueous solution of calcium oxide,

CaO

, because this compound will react with water to form calcium hydroxide,

Ca

(

OH

)

2

.

CaO

(

s

)

+

H

2

O

(

l

)

→

Ca

(

OH

)

2

(

a

q

)

+

energy

Keep in mind that this reaction is highly exothermic!

So, you can't talk about a solution that contains calcium oxide, which you'll maybe recognize as quicklime, because calcium oxide does not exist as such in aqueous solution, it exists as calcium hydroxide, or slacked lime.

Moreover, you should also keep in mind that calcium hydroxide is not that soluble in water to begin with, so chances are that some calcium hydroxide will precipitate out of the solution.

In your case, you're mixing

32.5

g

⋅

1 mole CaO

56.0774

g

=

0.5796 moles CaO

and

212

g

⋅

1 mole H

2

O

18.015

g

=

11.768 moles H

2

O

so the reaction will produce

0.5796

moles of calcium hydroxide--keep in mind that calcium oxide acts as a limiting reagent because of the

1

:

1

mole ratio that exists between the two reactants.

This is equivalent to

0.5796

moles Ca

(

OH

)

2

⋅

74.093 g

1

mole Ca

(

OH

)

2

=

42.9 g

of calcium hydroxide. So your resulting solution will contain

11.768 moles

-

0.5796 moles

=

11.188 moles H

2

O