Washing soda, a compound used to prepare hard water for
washing l...

Question

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 Na2CO3 # xH2O, where x is
the number of moles of H2O per mole of Na2CO3. When a
2.558-g sample of washing soda is heated at 125 C, all the
water of hydration is lost, leaving 0.948 g of Na2CO3. What is
the value of x?

Accepted Answer

Hi everyone here we have a question telling us that a 2.000 g sample of copper sulfate times X amount of water was heated until the water has been removed, The anhydrous salt was measured to have a mass of 1. g determine the value of X. For copper sulfate times X. Water. So first we need to calculate the molar mass of copper sulfate. So we have one copper With a molar mass of 0.54. And we have one sulfur With a molar mass of 0.6. And we have for oxygen With a molar mass of 16 And that equals 159 0.6. So now that we've got that we can determine the moles of copper sulfate. So we have one 278 g of copper sulfate times one mole Over its molar mass, which we just determined to be 159.6. So are grams of copper sulfate. Are canceling out and that equals 0.00 eight 008. And if we want to put that into scientific notation, we're going to take our decimal place and go to the right 1, 2, 3 places, which would make that 8. .008 Times 10 to the negative 3rd moles of copper sulfate. So now we want to do the same with water. We first have to add up its molar mass. So we have to hydrogen With a molar mass of 1.01 plus one oxygen With a mass of 16 And that equals 18.02. Now to find the moles of it, we want to take two g -1.278g and that will give us our grams of water. And then we're going to multiply that by one mole of water Over its molar mass. So 18.02 grams of water and our grams of water are canceling out here. And that gives us 0. moles of water. So now we need to take Our 0.04, 007 moles of water and divide it by Our 8.008 Times 10 to the negative 3rd moles of copper sulfate, And that equals five. So x equals five. And that is our final answer. Thank you for watching. Bye.

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