is this question right?!?

Question

Find the molority

there is 15 grams of Potassium Nitrate in 2 Liters of water.


and i got 9.6M is this right?

Answer 1

If you meant "molality" (moles per 1000 g of solvent) you can get an answer; if you meant "molarity" (moles per 1000 mL of solution) you can't get an exact answer because you don't know how many mL you will end with when you add 15 grams to 2000 mL of water...it will be slightly more than 2000 mL...my best guess is 2004 mL

compute the moles of KNO3; 15 g / 101 g per mole = 0.1485 moles.

0.1485 moles per 2000 g of water = 0.07425 molal
0.1485 moles per 2.004 L of water = 0.07410 molar

Since the weight was given to two significant figures, the answer to two significant figures is 0.074 molal or molar.

Answer 2

I presume you mean molarity (we never did molority)

First, find molecular weight of KNO3:

39 + 14 + [3 x 16] = 101g/mol

Now, determine number of moles:

15g/101g/mol = 0.149 mole

This quantity must be divided by the volume of the solution (2l)

0.149mol/2l = 0.0745M

Note:
Since they specified in the question there was 15g of KNO3 IN 2 liters of water (not 15 g ADDED TO 2 liters) you can get the exact answer for molarity!

Answer 3

NO.

First, convert 15 g of KNO3 to moles (15/102=0.147)

Then change to molarity. Molarity = moles/Liters

0.147 moles /2 Liters = 0.0735 M