Calculating the Neutralization of Acid in Grapefruit Juice

[sunfire249]

Homework Statement

Grapefruit juice contains approximately 0.75g/oz of citric acid (H3C6H5O7(aq)), a triprotic acid. If one tablet of Tums contains 500mg of CaCO3, would one tablet be able to neutralize the acid in one glass of grapefruit juice (8.0oz)? Show your calculations.

Therefore I found the relavant variables would be:
- 0.75g/oz of citric acid
- the fact that it's a triprotic acid
- the volume of one glass of grapefruit juice (8.0oz)
- the grams of tums (0.5g CaCO3)

Homework Equations

- Balancing the equation, which I had no idea how to do. I attempted to use the products H2O + CO2 + CaO, but I found I couldn't balance it.
- Dimensional analysis of the citric acid and CaCO3 from grams to moles

The Attempt at a Solution

1) Multiplied 0.75g/oz of Citric acid with the volume of citric acid (8.0oz) to get the grams of citric acid in grapefruit juice
2) I converted it to the moles of citric acid by dividing by the molar weight
So: 6.0g citric acid/193.1241g citric acid
3) I converted the amount of CaCO3 to moles as well

Not entirely sure where to go from here.

 

[symbolipoint]

Let us straighten this part first:

2. Homework Equations
- Balancing the equation, which I had no idea how to do. I attempted to use the products H2O + CO2 + CaO, but I found I couldn't balance it.
- Dimensional analysis of the citric acid and CaCO3 from grams to moles

You want to use CaCO3 to neutralize the triprotic citric acid. We could abbreviate the anion as something and say, the acid is symbolized as H3A.

Now, you want to balance CaCO3 + H3A -----> Ca... you may need to work a bit to show the actual products of the reaction. I will go ahead with this anyway.

CaCO₃ + H₃A -------> Ca₃A₂ + H₂O, but beware, I have NOT yet balanced the reaction, and I may possibly be incorrect in the Ca₃A₂ product. The reason is that I am not sure how likely the third proton of citric acid would be neutralized.

 

[Borek]

I guess question wants you to assume neutralization goes to completion. In reality that's not exactly true.