# Chemistry

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The solubility of benzoic acid in water is 2.56g in 100cm3 at 79 C and 0.29g in 100cm3 at 20 C. What is the minimum volume of water in which 1g of benzoic acid can be dissolved at 79 C?

I set up a dimensional analysis but since the question gives 2 sets of results, I do not know what to do.

• Chemistry -

The dimensional approach will work. The question asks for the minimun solubility AT 79 DEGREES C; therefore, just ignore the solubility of benzoic acid at 20 degrees C. As far as this problem goes, you don't really care what the solubility is at 20.

• Chemistry -

but what equation is used to find it? the delta H/RT equation won't solve for anything

• Chemistry -

I think you solve the first two given values and find delta H and then used the delta H to find solubility of water

• Chemistry -

what equation do you use??

• Chemistry -

The equation I would set up based on the information given is:

2.56g Benz. Acid /100cm^3 water = 1.00g Benz. Acid / x cm^3

Without the units,

2.56 /100 = 1.00 / x

Solve the above equation for "x" to get the minimum volume of water in cm^3 that would be needed to dissolve 1.00g of Benzoic acid.