## q and temp increase

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Emily Glaser 1F
Posts: 156
Joined: Thu Jul 27, 2017 3:01 am

### q and temp increase

If the q of a reaction is negative, does that mean that the temperature is decreasing.

If delta U is negative, does that indicate a temperature decrease

Lauren Seidl 1D
Posts: 51
Joined: Fri Sep 29, 2017 7:06 am

### Re: q and temp increase

Because q=n*C*deltaT, and neither moles nor molar heat capacity can be negative, a negative q would mean that delta T is negative. So yes, a negative q means that temperature is decreasing. A negative deltaU does not necessarily mean temperature is decreasing because deltaU=q+w. So even if q was positive (meaning an increase in temperature), the value of work could be negative enough to make deltaU a negative value.

siannehazel1B
Posts: 30
Joined: Fri Sep 29, 2017 7:06 am

### Re: q and temp increase

a negative q does not necessarily mean that the temperature will decrease as shown by the heat curve: The diagonal lines indicate an increase/decrease in temperature as a result of the change in energy, the flat parts of the graph show that energy is being added/removed however the temperature does not change (hence the flat line).