If 36.10 mL of 0.223 M of NaOH is used to neutralize a 0.515 g sample of citric acid, what is the molar mass of the acid?

Answer 1

Citric acid has a molar mass of "192 g/mol".

The balanced chemical equation for the neutralization reaction that takes place between sodium hydroxide, #NaOH#, and citric acid, #C_6H_8O_7#, looks like this
#C_6H_8O_(7(aq)) + color(red)(3)NaOH_((aq)) -> Na_3C_6H_5O_(7(aq)) + 3H_2O_((l))#
Notice the #1:color(red)(3)# mole ratio that exists between citric acid and sodium hydroxide; what this tells you is that, for every mole of citric acid, you need 3 times more moles of sodium hydroxide for the reaction to take place.
Since you know the molarity and the volume of the #NaOH# you've used, you can calculate how many moles of #NaOH# reacted
#C = n/V => n = C * V#
#n_(NaOH) = "0.223 M" * 36.10 * 10^(-3)"L" = "0.00805 moles"#

Now calculate the number of moles of citric acid contained in 0.515 g using the previously mentioned mole ratio.

#0.00805cancel("moles NaOH") * "1 mole citric acid"/(3cancel("moles NaOH")) = "0.00268 moles citric acid"#

To find the compound's molar mass, just divide the mass of citric acid by the number of moles it contained.

#M_M = m/n = "0.515 g"/("0.00268 moles") = "192.16 g/mol"#

When the number of sig figs for 0.515 g is rounded to three, the result is

#M_M = color(green)("192 g/mol")#

NOTE: Since citric acid's actual molar mass is 192.12 g/mol, your result is consistent with the value that is known.

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Answer 2

To find the molar mass of citric acid, first, determine the number of moles of NaOH used in the neutralization reaction using the given volume and concentration. Then, use the balanced chemical equation to find the mole ratio between NaOH and citric acid. Finally, calculate the molar mass of citric acid using the number of moles and the mass of the sample.

  1. Find moles of NaOH: [ \text{Moles} = \text{Molarity} \times \text{Volume (in liters)} ] [ \text{Moles of NaOH} = 0.223 , \text{mol/L} \times (36.10 , \text{mL} / 1000) ]

  2. Balance the neutralization reaction between NaOH and citric acid: [ \text{3NaOH} + \text{H}_3\text{C}_6\text{H}_5\text{O}_7 \rightarrow \text{Na}_3\text{C}_6\text{H}_5\text{O}_7 + \text{3H}_2\text{O} ]

  3. Use the mole ratio between NaOH and citric acid to find moles of citric acid.

  4. Calculate the molar mass of citric acid using: [ \text{Molar mass} = \frac{\text{mass}}{\text{moles}} ]

By following these steps, you can determine the molar mass of citric acid.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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