When a 6.50g sample of solid sodium hydroxide dissolves in 100.0g of water in a coffee cup calorimeter, the temperature rises from 21.6C to 37.8C.

A.) Calculate the quantity of heat (in kJ) released in the reaction.
(I know the answer, but can you show the steps)

Thanks

Where does 4.179 come from?

4.179 comes from the specific heat of water. if a specific heat capacity ("c") isn't given in a problem, it's pretty safe to assume "c" is 4.179 or 4.18 J/g-1 Kelvin (or celsius) if you are an IB chem student!

Well, aren't you just a hot cup of chemistry! Let's calculate the quantity of heat released in this reaction, shall we?

First, we need to calculate the heat gained by the water in the coffee cup. We can use the formula:

q = m * c * ΔT

Where:
q is the heat gained by the water
m is the mass of the water (100.0g)
c is the specific heat capacity of water (4.18 J/g°C)
ΔT is the change in temperature (37.8°C - 21.6°C)

q = (100.0g) * (4.18 J/g°C) * (37.8°C - 21.6°C)
q = 16680 J

Next, we need to convert this to kilojoules (kJ) because who wants to deal with all those extra zeros? We know that 1 kJ = 1000 J, so:

q = 16680 J / 1000
q = 16.68 kJ

Now, let's move on to the heat released by the sodium hydroxide. Since we know the temperature rise of the water, we can assume that the heat gained by the water is equal to the heat released by the sodium hydroxide. So:

q = -16.68 kJ

And there you have it! The quantity of heat released in this reaction is -16.68 kJ. Just keep in mind that the negative sign indicates that heat is being released, not gained. Stay cool!

Sure! To calculate the quantity of heat released in the reaction, you can use the formula: q = m × c × ΔT, where q is the heat released or absorbed, m is the mass of the substance, c is the specific heat capacity of the substance, and ΔT is the change in temperature.

First, let's calculate the heat released by water using the formula above:
m = 100.0 g (the mass of water)
c = 4.18 J/g·°C (specific heat capacity of water)

ΔT = (final temperature) - (initial temperature)
ΔT = 37.8°C - 21.6°C = 16.2°C

Now, we can substitute the values into the formula:
q_water = m × c × ΔT
q_water = 100.0 g × 4.18 J/g·°C × 16.2°C

The next step is to convert the heat from joules to kilojoules since the question asks for the answer in kJ. To do this, divide the result by 1000:
q_water = (100.0 g × 4.18 J/g·°C × 16.2°C) / 1000
q_water = 6.7936 kJ (rounded to four decimal places)

The heat released by the solid sodium hydroxide is equal in magnitude but opposite in sign to the heat released by the water. Therefore, the heat released by the solid sodium hydroxide is -6.7936 kJ (negative because it is released).

So, the quantity of heat released in the reaction is approximately -6.7936 kJ.

temp change times mass of H2O times specific heat of H2O

(37.8 - 21.6) * 100 * 4.179

remember sig fig