For the system CaO(s) + CO2(g) = CaCO3(s), I added 1.00 mol of CaO(s) to 1.00L of 0.500M CO2(g) at 200 oC. At equilibrium the [CO2] = 0.150M. What is the value of Kp for this reaction?
Kp would = CaCO3/(CaO)(CO2)
I do not know what to do with the 0.500M and 1.00mol.
Chemistry(Please help) - DrBob222, Wednesday, March 14, 2012 at 10:32pm
First you need to work on the Kp expression. SOLIDS aren't used (pure liquids aren't either) so the expression is 1/pCO2 = Kp.
The problem tells you that AT EQUILIBRIUM [CO2] = 0.150M.
I would calculate Kc from Kc = 1/([CO2]
then convert to Kp by Kp = Kc(RT)Dn
So I did 1/0.150 and got 6.66 so now I use this with RT. I am not sure what R is? Kp=6.66(200C + 273)(R)??
I thought one of the first constants one learned in chemistry from the PV = nRT equation was R. R = 0.08206 L*atm/mol*K.
ok so 6.66(473K)(0.08206) = 258.5 which would be 2.59 which is one of the answer choices. Does this seem correct??
the R will be molecular mass of the equation of the reaction
I don't think so.
Kp = Kc(RT)Dn.
You have Kc, R, T but you don't have delta n anywhere in the equation. Also, note that it is NOT R*Tdelta n but (RT)delta n
Hannah, I understand that you are having trouble with the homework but academic dishonesty is not the answer. I will be flagging your academic transcripts by the end of today, please come speak with me as soon as you can, maybe we can work something out.
To determine the value of Kp for the given reaction, you need to follow these steps:
Step 1: Write the balanced equation for the reaction:
CaO(s) + CO2(g) = CaCO3(s)
Step 2: Identify the substances involved in the reaction:
- CaO(s) is a solid and doesn't appear in the Kp expression.
- CO2(g) is a gas and will be included in the Kp expression.
- CaCO3(s) is a solid and doesn't appear in the Kp expression.
Step 3: Determine the Kp expression:
For a reaction involving gases, the Kp expression is written as the partial pressure of the gaseous products raised to the power of their stoichiometric coefficients divided by the partial pressure of the gaseous reactants raised to the power of their stoichiometric coefficients.
In this case, since only CO2(g) is a gas, the Kp expression becomes:
Kp = pCO2
Step 4: Given information:
- [CO2] at equilibrium = 0.150 M
Step 5: Convert to partial pressure:
To calculate the partial pressure of CO2, you need to know the relationship between concentration and partial pressure. At low pressures or when the ideal gas law is applicable, you can assume the molar concentration is proportional to the partial pressure.
Assuming the ideal gas law holds at 200°C, you can convert the concentration of CO2 to partial pressure (pCO2) by using the formula pCO2 = [CO2] * RT, where R is the ideal gas constant and T is the temperature in Kelvin.
However, since you have the value of [CO2] in Molarity (M), you need to convert it to atmospheres (atm) first. The ideal gas constant R is 0.0821 L.atm/mol.K.
So, pCO2 = [CO2] * RT = (0.150 M) * (0.0821 L.atm/mol.K) * (200°C + 273) = ?
Remember to convert the temperature to Kelvin by adding 273 since the gas constant is in Kelvin.
By calculating the above expression, you will obtain the value for pCO2.
Step 6: Calculate Kp:
Once you have obtained the value for pCO2, you can substitute it into the Kp expression:
Kp = pCO2 = ?
By substituting the value into the Kp expression, you will obtain the result for Kp.