## qv vs qp

$\Delta U=q+w$

Harmony Becerra
Posts: 32
Joined: Sun Jan 21, 2018 3:00 am

### qv vs qp

What is the difference between qv and qp and how do we know when we should use each of them?

Giselle1B
Posts: 26
Joined: Fri Sep 28, 2018 12:19 am

### Re: qv vs qp

Qv is heat in constant volume and qp is heat in constant pressure. Typically, the questions will ask you specifically which one to solve by.

Nicole Elhosni 2I
Posts: 62
Joined: Fri Sep 28, 2018 12:28 am

### Re: qv vs qp

Q is equal to enthalpy when the pressure is kept constant, so Qp is always equal to enthalpy.

josephperez_2C
Posts: 70
Joined: Wed Nov 15, 2017 3:04 am

### Re: qv vs qp

q(v) is heat at constant volume and q(p) is heat at constant pressure

Sarah Fatkin 4I
Posts: 71
Joined: Fri Sep 28, 2018 12:27 am

### Re: qv vs qp

Qv is heat at constant volume, while Qp is heat at constant pressure. At constant volume, delta(U) = Qv, because no work is being done on the system. At constant pressure, delta(U) = delta(H) - p(delta(V)). Hope this helps!

g orloff 1J
Posts: 45
Joined: Fri Sep 28, 2018 12:16 am

### Re: qv vs qp

qv is heat at a constant volume qp is heat at a constant pressure.

daniella_knight1I
Posts: 57
Joined: Fri Sep 28, 2018 12:18 am

### Re: qv vs qp

qv is constant volume and qp is constant pressure denoted by the sub letters v and p.

Brian Hom 2F
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: qv vs qp

qv is heat at a constant volume while qp is heat at a constant pressure. qp is usually measured with a calorimeter while qv can be measured with a bomb calorimeter.qp also equals delta H or enthalpy where pressure is constant. At a constant volume, deltaU = qv, since no work of expansion is being done on the system. At a constant pressure, deltaU = deltaH- pdeltaV.

Aleeque Marselian 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: qv vs qp

qv is heat at constant volume, while qp is heat at constant pressure, as denoted by the subscripts. The question would typically ask you which one to solve for or would typically state which one is constant. Hope this helps!

Joanna Pham - 2D
Posts: 113
Joined: Fri Apr 06, 2018 11:04 am

### Re: qv vs qp

Aleeque Marselian 1A wrote:qv is heat at constant volume, while qp is heat at constant pressure, as denoted by the subscripts. The question would typically ask you which one to solve for or would typically state which one is constant. Hope this helps!

just wondering, if a question asked us to solve for Qv or Qp, how would we solve it? Is there a formula? Correct me if I am wrong, but I don't recall ever being given an exact formula to solve for these...