The following reaction can be used to determine the amount of calcium ion present in milk. Before the reaction below is carried out ca2+ is precipitated out of a sample of milk as CaC2O4(s). The CaC2O4(s) is then titrated with MnO4-.
2MnO4-(aq) + 5CaC2O4(s) + 16H+(aq) = 2Mn2+(aq) + 5Ca2+(aq) + 10CO2(g) + 8H2O(l)
(delta H) = -1535 kJ
A quantity of CaC2O4(s) is obtained by precipitating Ca2+ from a 660.-ml sample of milk. It takes 34.0 ml of 0.225 M MnO4- to titrate the CaC2O4.
a. How many moles of MnO4- were used in the titration?
mols MnO4^- = M x L
b. what is the concentration (molarity) of Ca2+ in the milk sample?
Use the coefficients in the balanced equation to convert moles MnO4^- to moles Ca^+2.
moles Ca^+2 = moles MnO4^- x (5 moles CaC2O4/2MnO4^-) = ??moles MnO4^- x (5/2) = xx moles Ca^+2
Then molarity Ca^+2 = xx moles Ca^+2/0.660L
c. how much heat, in kJ, was given off by the reaction during the titration? Is that 1535 kJ for the reaction? If so, then (1535 kJ/5 mole) x (xx moles CaC2O4) = ??
d. If the titration was performed at 0 C and 1 atm of pressure, what volume of CO2 was produced during the titration?
Convert moles MnO4^- to moles CO2 (the same process used in the part b above), then use PV = nRT to calculate volume OR the simpler way is to recognize that OC and 1 atm is STP and you know 1 mole of a gas occupies 22.4L at STP; therefore, moles CO2 x 22.4 = volume (in liters) of CO2 gas.
The following reaction can be used to determine the amount of calcium ion present in milk. Before the reaction below is carried out ca2+ is precipitated out of a sample of milk as CaC2O4(s). The CaC2O4(s) is then titrated with MnO4-.
2MnO4-(aq) + 5CaC2O4(s) + 16H+(aq) = 2Mn2+(aq) + 5Ca2+(aq) + 10CO2(g) + 8H2O(l)
(delta H) = -1535 kJ
A quantity of CaC2O4(s) is obtained by precipitating Ca2+ from a 660.-ml sample of milk. It takes 34.0 ml of 0.225 M MnO4- to titrate the CaC2O4.
a. How many moles of MnO4- were used in the titration?
b. what is the concentration (molarity) of Ca2+ in the milk sample?
c. how much heat, in kJ, was given off by the reaction during the titration?
d. If the titration was performed at 0 C and 1 atm of pressure, what volume of CO2 was produced during the titration?
IF you could help me by answering and showing how you did it (equations) that would be great.
Thanks.
1 answer