Finding the formula of a sodium carbonate hydrate by titration with HCl

[Zoey Brown]

Homework Statement

The formula of a hydrate may be determined by titarion. If 2.316g of a hydrate of sodium carbonate is required to completely neutralize 38.49 mL of 0.4198 mol/L HCl,find the formula of the hydrate. The products will be NaCl, H20, and CO3

Homework Equations

n=cv
m=mM

The Attempt at a Solution

Na2CO3 . xH20 --> Solving for x
find moles of HCL
Use mole ratios

 

[symbolipoint]

You are titrating (measuring) the amount of sodium carbonate in the sample. The rest would be water (the water of hydration).

 

[Zoey Brown]

so does the 2.316g not include the xh2o?

 

[Borek]

so does the 2.316g not include the xh2o?

It does. But the titration result tells you how many moles of Na₂CO₃ are present, regardless of how much hydration water it contains.

 

[Zoey Brown]

so if I've found that there are 0.00807906 mol of Na2CO3, where would i go from there to find the formula of the hydrate?

 

[Borek]

What is the mass of the 0.008079 moles of the sodium carbonate?

 

[Zoey Brown]

would it be 2.316 g

 

[symbolipoint]

Na₂CO₃ + 2HCl -----------> 2NaCl + H₂O

Formula weight for sodium carbonate is 105.999 grams per mole
Formula weight for hydrogen chloride is --- will not be needed

 

[Borek]

would it be 2.316 g

Don't guess - calculate.