EricRivers - 20-11-2013 at 18:40
When 50 grams each of 1.0 M HCL and 1.0 M NaOH are mixed, the enthalpy of reaction is determined to be -2.85 kj
1. Write a balance chemical reaction.
- HCL + NaOH---> NaCL + H20
2. Determine the number of moles of HCL and NaOH that reacted.
- Number of HCL that reacted-- 1.4 mol HCL
- Number of NaOH that reacted-- 1.25 mol NaOH
3. How many moles of water were generated.
- 1.25 mol of water
4. Calculate kJ/ mol of H20 for this reaction.
?? Not sure
This is my attempt at the problems, I'm just having a tough time. Any help with this problem and explanation would be appreciated. And let me know if
my answers are right so far! Thank you 
Metacelsus - 20-11-2013 at 19:10
Step 2 is wrong. Find your limiting reactant.
Also, using mass and molarity together is strange. You have to adjust for the solution density. Are you sure you didn't mean 50 ml of each?
[Edited on 21-11-2013 by Cheddite Cheese]
EricRivers - 20-11-2013 at 19:18
number of moles of HCL and NaOH is wrong? and yes the question is 50 grams
EricRivers - 20-11-2013 at 19:44
Is my limiting reactant NaOH? so the number of HCL that reacted is 1.25 mol and the number of NaOh that reacted is 1.25 mol??
Homework Question
EricRivers - 21-11-2013 at 05:33
When 50 grams each of 1.0 M HCL and 1.0 M NaOH are mixed, the enthalpy of reaction is determined to be -2.85 kj
1. Write a balance chemical reaction.
- HCL + NaOH---> NaCL + H20
2. Determine the number of moles of HCL and NaOH that reacted.
- Number of HCL that reacted-- 1.25 or 1.4 mol HCL??
- Number of NaOH that reacted-- 1.25 mol NaOH
3. How many moles of water were generated.
- 1.25 mol of water
4. Calculate kJ/ mol of H20 for this reaction.
?? Not sure
This is my attempt at the problems, I'm just having a tough time. Any help with this problem and explanation would be appreciated. And let me know if
my answers are right so far! Thank you
Metacelsus - 21-11-2013 at 05:49
1 M NaOH density is 1.04 g/ml (at 25 C). So you will have 48.1 ml of 1 M NaOH, which is 0.0481 moles. You can determine the moles of HCl in a similar
way.
bfesser - 21-11-2013 at 05:57
<strong>EricRivers</strong>, please don't double or cross-post. You won't get help any quicker (or friendlier!) that way. [merged
double-post]
DraconicAcid - 21-11-2013 at 09:08
I'm sure the person issuing the homework wanted to keep it simple, and let the student assume a density of 1 (because that's what I generally do). 50
mL gives you 50 mmol of each reactant. This will result in an enthalpy change of -2.85 kJ, but this is not the enthalpy of reaction. The enthalpy of
reaction is the molar enthalpy change for the reaction, and I wish people would stop mixing the two up. That's like using "mass" and "molar mass"
interchangeably.
Paddywhacker - 21-11-2013 at 16:24
Cheddite is correct. Molarity is by volume, not by weight, so the density has to be used to calculate the volumes used.