CHEMISTRY HOMEWORK QUESTION! CONFUSED! HELP?
Topic: Chemistry homework questions
May 24, 2019 / By Gena Question:
The alum used in cooking is potassium aluminum sulfate hydrate, KAl(SO4)2·xH2O. To find the value of x you can heat a sample of the compound to drive off all the water and leave only KAl(SO4)2. Assume that you heat 5.834g of the hydrated compound and that it loses 2.25g of water. What is the value of x? (enter as an integer).
Best Answers: CHEMISTRY HOMEWORK QUESTION! CONFUSED! HELP?
Deeann | 6 days ago
Here is the same question using different numbers. The answer should guide you in how to come up with the answer you need.
The "alum" used in cooking is potassium aluminum sulfate hydrate, KAl(SO4)2·x H2O. To find the value of x, you can heat a sample of the compound to drive off all of the water and leave only KAl(SO4)2. Assume you heat 4.74 g of the hydrated compound and that the sample loses 2.16 g of water. What is the value of x?
your sample, pure, is 2.58g (4.74-2.16)
That converts into 0.01 mol of KAl(SO4)2
then you find how many moles of water evaporated.
(2.16/18) = 0.12mol of H2O
We now know that for every 1 mole of KAl(SO4)2, there were 12 moles of water.
x = 12!
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Originally Answered: Chemistry homework so confused?
( 5.86 kJ/°C) x (29.5 - 25.8)°C = 21.682 kJ
(0.469 g C12H10) / (154.2088 g C12H10/mol) = 0.0030413 mol C12H10
(21.682 kJ) / (0.0030413 mol C12H10) = 7129 kJ/mol C12H10
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Originally Answered: Confused in Chemistry and homework?
Do you literally mean "atoms" in K2Cr2O7, because there are 11 moles of atoms in 1 mol of the salt.
Use the unit-factor method and the appropriate conversion factors.
18.4 g K2Cr2O7 x (1 mol K2Cr2O7 / 294.2 g K2Cr2O7) x (11 moles atoms / 1 mol K2Cr2O7) x (6.022x10^23 atoms / 1 mol atoms) = 4.14x10^23 atoms
You started with a mass with 3 sig figs, so you'll end up with 3 sig figs in the answer.