CHEMISTRY COMMUNITY

Julia Holsinger_1A

When using the equation (delta)S= C ln(T2/T1), How do you know which heat capacity to use?

Julia Holsinger_1A

Also when there is constant pressure and no expansion work, (delta)H=q

Julia Holsinger_1A

Like the diagram in class, you can tell that there is a phase change when the heat or enthalpy is increasing, but the temperature is not increasing, or delta T is zero. Can the enthalpy increase AND the temperature remains the same while there still not being a phase change? Like I'm imagining the ...

Julia Holsinger_1A

Would there ever be a first order linear slope that is positive and not negative?

Julia Holsinger_1A

How do you spot a catalyst in a reaction? Or will it always be given?

Julia Holsinger_1A

I convert RT/F to 0.025693 V and it has always given me the correct answer when I plug it in. I think you need to be careful of how you round if you are calculating RT/nF

Julia Holsinger_1A

For question 6 part b) How will each of the following changes affect the cell potential: i) adding 100 mL pure water to cathode solution ii) halving the mass of anode electrode I am a bit confused with i) and how the cell potential would decrease when adding 100mL of water into the solution because ...

Julia Holsinger_1A

make sure to set up the equation by first isolating ln(K2). So the equation would be: ln(K2)=(deltaH/R) (1/T1 - 1/T2) + ln(K1). Then plug in your numbers. I have found that when I don't isolate the ln(K2) first I get a strange answer.

Julia Holsinger_1A

In the text book I am seeing lots of equations that have (delta)G sub r, what does the r mean? I think its just reaction but I am not positive.

Julia Holsinger_1A

When the equilibrium constant K is larger than 10^3 does the reaction favor the products or the reactants?

Julia Holsinger_1A

How do you determine the order of the reaction when needing to calculate half life? Will it always be given? To determine the order, you will likely use scientific data, are told, or can assume pseudo-first reaction if the information permits. I am a bit confused about psuedo-first reaction, could ...

Julia Holsinger_1A

How do you determine the order of the reaction when needing to calculate half life? Will it always be given?

Julia Holsinger_1A

How do you determine time (t) when given half life and the percentage something has decreased? EX: from self-test 7B.4A: In 1972, grain treated with methyl mercury was released for human consumption in Iraq, resulting in 459 deaths. The half-life of methyl mercury in body tissues is 70 days. How man...

Julia Holsinger_1A

Does anyone know how much time we will be given to do the final?

Julia Holsinger_1A

How do you find the limiting step?

Julia Holsinger_1A

It is the slowest step in the reaction

Julia Holsinger_1A

when trying to determine k, can you use any trial (when looking at multiple trials)?

Julia Holsinger_1A

From Lavelle's Week 10 Review slides that he posted, On the first slide, how do you get the change in molar concentration? I am confused with how 0.075 and 0.225 were calculated.

Julia Holsinger_1A

When balancing basic half reactions, how do you know which side to put the OH- versus the H2O?

Julia Holsinger_1A

005384106 wrote:At what point do you add elections to the half reaction?

When all other elements are balanced and you just need to balance the charge of both sides

Julia Holsinger_1A

005384106 wrote:Why do we measure the voltage difference of two cells?

The difference in potential voltage is what gives rise to electric current

Julia Holsinger_1A

Ecell and K are positively related so the larger the K means a more positive Ecell

Julia Holsinger_1A

Julia Holsinger_1A

What does the w in pKw stand for?

Julia Holsinger_1A

bloodorangefield wrote:How do you tell the difference between when it is an anode vs when it is cathode?

anode is always on the left and cathode is on the right

Julia Holsinger_1A

Will the 2nd order slope ever be negative when plotting?

Julia Holsinger_1A

How do you know to use Van't Hoff Equation? Are there certain questions in problems that signal to use it?

Julia Holsinger_1A

Also what is the relationship between the constants and solubility? are they positively correlated or negatively correlated?

Julia Holsinger_1A

How do you use Equilibrium constants to predict solubility? Would you use Le Chatelier's principle?

Julia Holsinger_1A

What is the difference between pKa and Ka? same for pKb and Kb.

Julia Holsinger_1A

How do you figure out the conjugate acid or base for a given base or acid?

Julia Holsinger_1A

How do you distinguish if something is an ideal gas?

Julia Holsinger_1A

What is the relationship between work and cell potential?

Julia Holsinger_1A

What are the rules for oxidation numbers? I am having trouble getting the n in while trying to calculate the Gibbs Free Energy when given cell potential.

Julia Holsinger_1A

Asha Agarwal 1E wrote:Can someone also explain #12B? Is there a specific equation to use?

You take the q=mC(delta)T of each part of the equation while using the Cpm values given for C and then you do the sum of the products minus the sum of the reactants.

Julia Holsinger_1A

I am confused with #12B. What equation do you use when trying to find delta H?

Julia Holsinger_1A

Standard entropies tend to increase with increasing molar mass.

Julia Holsinger_1A

Could someone please summarize this chart please? What is R and why would it be the way it is on the chart? the gas chart is for monoatomic and diatomic ideal gases. Monoatomic Internal energy: 3/2nRT . Monoatomic molar Cv: 3/2 R . Monoatomic molar Cp: 5/2 R Diatomic Internal energy: 5/2nRT . Diato...

Julia Holsinger_1A

When are you supposed to use the chart for the monoatomic and diatomic that give Molar heat capacities? (ex. 3/2 R)

Julia Holsinger_1A

For constant pressure the equation is W= -P(delta)V , what is the equation for constant volume?

Julia Holsinger_1A

When do you use the Van Hoff equation?

Julia Holsinger_1A

Work will be negative if the system is expanding and will be positive if the system is compressing.

Julia Holsinger_1A

How do you know to use the integral when calculating the Work of Expansion?

Julia Holsinger_1A

How do you calculate the molar heat capacity?

Julia Holsinger_1A

How can you prove that the total enthalpy change is the sum of the changes in it?

Julia Holsinger_1A

Does gibbs free energy determine spontaneity and enthalpy? Or only enthalpy?

Julia Holsinger_1A

I believe ICE table only pertains to gases

Julia Holsinger_1A

I am still getting 2.2 even when I calculate the concentration of H2 and AsH3 by divided moles by 3.00L

Julia Holsinger_1A

Jaci Glassick 2G wrote:I know this is a bit away, but does anyone what topics will be covered on Test 1? Thank you!

Chemical Equilibrium and Acid and Base Equilibria

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