chemistry problems?

Question

Part one Heat of Solution:
If 4.436 g of NaOH was added to 150.0 mL of water
and we assume the density of water to be 1.000 g/mL
then what is the total mass? (Watch your Sig. Figs.)

If in part one, 4.436 g of NaOH was weighed out. How many moles of NaOH is this ?

Given that the temperature change observed was 11.5 C
when 4.436 g of NaOH were added to 150.0 mL of water.
What is the heat energy in kJ that is produced. (Don't
forget the specific heat of this SOLUTION is 4.06 j/ g C.)

Lets say that the heat produced when 4.436 g of NaOH was added to a water solution was 6.123 kJ. What is the calculated heat of solution (hint kJ/mole)?

These are some practice quiz problems Im having trouble with. Thanks.

Answer 1

(150.0 mL)*(1.000 g/mL) + 4.436g = 154.4 g

The formula mass of NaOH is: 39.9971 g/mol
4.436 g/(39.9971 g/mol) = 0.1109 mol

(4.06 j/gC)*(154.4 g)*11.5 = 7.21 kJ

6.123kJ/ (0.1109 mol) = 55.21 kJ/mol

Answer 2

where did you get the 6.123 kJ/mole from ?