## 8.67

$\Delta U=q+w$

Samira 2B
Posts: 38
Joined: Fri Sep 29, 2017 7:05 am

### 8.67

For a. when calculating bond enthalpies one finds the enthalpy of formation for water in its gas state. However, the equation has water in its liquid state. So, how do we know that water is in its gas state versus knowing it is in its liquid state?

Srbui Azarapetian 2C
Posts: 54
Joined: Thu Jul 13, 2017 3:00 am
Been upvoted: 2 times

### Re: 8.67

The reaction for 1 mol of gaseous water is H2(g)+1/O2(g)->H20(g). The question asks for to find the enthalpy of formation of liquid water. This involves use of the equation: Enthalpy of formation of liquid water = Enthalpy of formation of gaseous water- Enthalpy of vaporization to account for the phase change.

Thu Uyen Tran 1B
Posts: 31
Joined: Fri Sep 29, 2017 7:05 am

### Re: 8.67

The solutions manual had the reaction H2(g)+1/O2(g)->H20(l). How can we know what phase any product is in, especially H2O?

Kayla Tchorz-Dis 1F
Posts: 30
Joined: Thu Jul 13, 2017 3:00 am

### Re: 8.67

For this, I'm also confused how you are supposed to combine the use of bond enthapies and also the enthalpy of formations.

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