Problem: Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of water molecules are included in the solid structure. Its formula can be written as Na2 CO3 xH2 O, where x is the number of moles of H2 O per mole of Na2 CO3. When a 2.814 -g sample of washing soda is heated at 25 oC, all the water of hydration is lost, leaving 1.04 g of Na2 CO3.What is the value of x?

FREE Expert Solution

We’re asked to determine the value of x in washing soda, (Na2CO3•xH2O)if heating a 2.814 -g sample leaves 1.04 g of Na2CO3.


Recall that hydrates such as washing soda lose its water of hydration upon heating


This means that to solve for x which is the number moles of H2O per mole Na2CO3we need to do the following steps: 


Step 1: Determine the mass of water of hydration, H2O evaporated :


Mass H2O = Na2CO3•xH2O -  mass Na2CO3


Step 2: Determine the moles of H2O and Na2CO3 to solve for x


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Problem Details

Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of water molecules are included in the solid structure. Its formula can be written as Na2 CO3 xH2 O, where x is the number of moles of H2 O per mole of Na2 CO3. When a 2.814 -g sample of washing soda is heated at 25 oC, all the water of hydration is lost, leaving 1.04 g of Na2 CO3.


What is the value of x?

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Mole Concept concept. You can view video lessons to learn Mole Concept. Or if you need more Mole Concept practice, you can also practice Mole Concept practice problems.

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Based on our data, we think this problem is relevant for Professor Shaka's class at UCI.