CHEMISTRY COMMUNITY

Sanmeet Atwal 1D

Justin's right, for this class we use the pre-equilibrium approach to find the overall rate law!

Sanmeet Atwal 1D

Hi Glenda! This is explained on page 72 of the course reader! But basically for part a) you know that CH3CHO ---> CH3 + CHO so you know that the CH3CHO bond is breaking into CH3 and CHO and you would represent this by [CH3........CHO] to depict where the bond is breaking. and you would do the same t...

Sanmeet Atwal 1D

It's not reaction 2 because the energy of the products is higher than the reactants so the reaction is endothermic and non spontaneous, whereas reaction 1 is exothermic and spontaneous so lowering the activation energy would benefit reaction 1 more because it would favor the products.

Sanmeet Atwal 1D

I would make sure to understand the homework problems because often times they will be repeated on the midterm/final. As long as you understand the concepts in the homework problems well, I believe you should be fine!

Sanmeet Atwal 1D

When a solid turns into a liquid you know that heat is absorbed and q is positive and since the change is occurring at a constant temperature you know that ΔU = 0. From here you can use the formula: ΔU = q+w = 0 to solve for w. If w is positive you know that work was done on the system and if w is n...

Sanmeet Atwal 1D

I'm not entirely positive but I believe you're right because molecules have rotational and translational energy while atoms only have translational energy!

Sanmeet Atwal 1D

We have to write the reaction like this in the beginning: H2(g) + 1/2 O2(g) ----> H20 (l) ΔHformation: -286 kJ because the standard enthalpy of formation of water for one mol is: -286 kJ so in the reaction you want one mol of water which means 02 has to have 1/2 as the coefficient for it to be balan...

Sanmeet Atwal 1D

If you know the molar heat capacity and the specific heat capacity you can calculate the molar mass of the element and then find it on the periodic table: Molar Heat Capacity: 3R = 3 (8.314 J/k/mol) Specific Heat Capacity: 0.392 J/k/g We know that the molar heat capacity = specific heat capacity * m...

Sanmeet Atwal 1D

I think it's fine as long as you know to use grams when using specific heat capacity Cs and use moles when using molar heat capacity Cm because the units would cancel out in each case!

Sanmeet Atwal 1D

The solutions manual depicts the reaction as 60C(gr)----->60C(g) bond enthalpy: 60(+717kJ/mol) = +43030 kJ/mol and then forming 60 mol of C-C single bonds and 30 mol of C=C double bonds. We know that when a bond is formed it's an exothermic process and releases energy so you would multiply 60 and 30...

Sanmeet Atwal 1D

There are two parts to this problem since you need to melt the 80.0 grams of ice at 0.00 degrees C and then heat the liquid water to 20 degrees C. So you need to find the heat needed in order to melt the ice and add it to the heat needed to heat the water to 20 degrees C. 1.) In order to find ΔH of ...

Sanmeet Atwal 1D

Problems 7.27 and 7.29 are directly related to section 7.10!

Sanmeet Atwal 1D

The formula for change in internal energy is: Δu= q+pΔV This question uses information given in example 7.4. We know from example 7.4 that it's placed in a constant-volume calorimeter so the change in volume=0 which means that pΔV=0 so Δu=q+0. We also know from the given information in 7.4 that the ...

Sanmeet Atwal 1D

In the text they say: "a reversible process is one that can be reversed by an infinitely small change in a variable (an “infinitesimal” change). For example, if the external pressure exactly matches the pressure of the gas in the system, then the piston moves in neither direction. If the extern...

Sanmeet Atwal 1D

The book gets 5/2 R from the chart: IMG_4189.jpg Since Kr is an atom and you're trying to find heat released at constant pressure you use the Cp,m for an atom on the chart which is 5/2R. They get 20.8 J*mol^/1 which is Cp,m when they multiply 5/2 by the Gas Constant R! From there they use the equati...

Sanmeet Atwal 1D

7.29 Predict the contribution to the heat capacity CV,m made by molecular motions for each of the following atoms and molecules: (a) HCN; (b) C2H6; (c) Ar; (d) HBr. You have to use the chart in the textbook on page 255: IMG_4189.jpg Since Ar is an atom and you're trying to find the Cv,m which means ...

Sanmeet Atwal 1D

Change in U (internal energy) = 0 for an ideal gas(pg.248). Internal energy is a state function because it only depends on the current state but heat(q) and work(w) are not state functions. I think if the system does work it loses some energy so some heat would flow back in to make up for the lost e...

CHEMISTRY COMMUNITY

Search found 17 matches

Re: When to use steady-state vs. pre-equilibrium

Re: Drawing proposed structures for an activated complex

Re: Decrease in Activation Energy

Re: Equipartition Theorem

Re: 7.15 clarifications

Re: Does a monatomic atom have rotational motion?

Re: Hess's Law, Multiplying Coefficients

Re: HW 7.33

Re: Cs and Cm

Re: HW #109b

Re: Hw 7.37

Re: Heat Capacity of ideal gas

Re: Self-test 7.4 A

Re: Understanding reversible, isothermic expansion

Re: Molar heat capacity of an ideal monatomic gas

Re: Contribution to the heat capacity

Re: Why E=0 for isothermal processes?