How to Calculate the Mass of Anhydrous Cu(NO3)2 from Its Hydrate?

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In summary, the mass of anhydrous compound refers to the weight of a substance with all water molecules removed. This is determined through a process called dehydration and is important in scientific research for accurate measurements. The mass can change over time due to environmental factors. Anhydrous compounds differ from hydrous compounds in that they do not contain water molecules, which can impact their properties and mass.
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Homework Statement
What is the mass of the anhydrous compound in [tex]Cu(NO_{3})_{2} * 2.5 H_{2}O[/tex]
, in other words, the [tex]Cu(NO_{3})_{2}[/tex], if 4.875g of the hydrated compound is used?


The attempt at a solution
What I did was find the formula mass of [tex]Cu(NO_{3})_{2}[/tex] which turned out to be 187.57g
Cu= 1 * 63.55 = 63.55
N= 2 * 14.01 = 28.02
O = 6 * 16.00 = 96.00

The formula mass of the water is 45.05g
H= 2.5(1.01 * 2) = 5.05g
O= 2.5(16.00 * 1) = 40g

From here I set up a ratio:
4.875/232.62 = x/187.57
x = 3.931g of [tex]Cu(NO_{3})_{2}[/tex]

Is this right?
 
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The method looks good.
 
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I would like to confirm that your approach and calculations are correct. You have correctly determined the formula mass of Cu(NO_{3})_{2} and the hydrated compound. Your use of ratios to find the mass of the anhydrous compound is also appropriate. Your final answer of 3.931g of Cu(NO_{3})_{2} is correct. Good job!
 

1. What is the definition of "mass of anhydrous compound"?

The mass of anhydrous compound refers to the total weight of a substance when all of its water molecules have been removed.

2. How is the mass of anhydrous compound determined?

The mass of anhydrous compound is determined through a process called dehydration, where the substance is heated to remove all water molecules. The remaining solid is then weighed to determine its mass.

3. Why is the mass of anhydrous compound important in scientific research?

The mass of anhydrous compound is important in scientific research because it allows scientists to accurately measure the quantity of a substance without the interference of water molecules. This is crucial in determining the purity and composition of a compound.

4. Can the mass of anhydrous compound change over time?

Yes, the mass of anhydrous compound can change over time due to factors such as exposure to humidity or temperature changes. This is why it is important to store anhydrous compounds in a controlled environment.

5. What is the difference between anhydrous and hydrous compounds?

Anhydrous compounds do not contain any water molecules, while hydrous compounds have water molecules incorporated into their molecular structure. This can affect their physical and chemical properties, as well as their mass.

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