Finding the total mass of a solution

[Lnettie21]

Can you help me with these two questions please

 

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?

 

 

 

Given that the temperature change observed was 11.5 C when4.436 g of NaOH were added to 150.o mL of water, What is the heat energy in kJ that is produced. (Don't forget the specivic heat of this solution is 4.06j/g C and assume the density of water to be 1.000 g/mL)

 

Thanks

[blike]

For the first question, you are given 4.436g as your NaOH mass. You are also given the density and volume of water it has been added to.

 

You need to convert your water's volume to mass:

 

150.0mL H2O * (1.000 g/mL) = 150.0 g H2O.

 

Now simply add the two masses: 150g + 4.436g = 154.436g

 

You try the second part on your own

[wolfson]

Looks good to me blike

[chemistry]

You have the total mass of the solution. You also have the specific heat...use

 

q=ms(dT)

[wolfson]

q=ms/_\T = m s (tf – ti)

 

tf = final temperature of substance

ti = initial temperature of substance

 

where m = mass and s = J/g per degree c

 

Chemistry just thought id tell me/her what the symbols are.

[Lnettie21]

Thanks Everyone. For the second part, I got 154.436*4.06*11.5=7,210.617. Is this correct? This number is kind of high

[wolfson]

7.2 KJ seems fine