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posledela
3 years ago
9

gypsum is hydrated calcium sulfate. a 4.89 g sample of this hydrate was heated, and after the water was driven off, 3.87 g anhyd

rous calcium sulfate remained. determine the formula of this hydrate and name the compound
Chemistry
1 answer:
Paha777 [63]3 years ago
7 0
You have to find the number of moles of water and calcium sulfate.  
to find the mass of water you subtract 3.87 by 4.89 to get 1.02g water and we are given taht the mass of calcium sulfate is 3.87g
then find the moles of water and calcium sulfate in the sample
1.02/18=0.05667mol water
3.87/136.2=0.0284 mol water
now you have to find how many moles there are per one mole of calcium sufate.
0.05667/0.0284=1.994 which can be rounded to 2 mol water for ever 1 mol calcium sulfate
therefore the formula for this CaSO₄·2H₂O and is called calcium sulfate dihydrate.

I hope this helps
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What is the pH of this solution?
Vesnalui [34]

Answer:

pH = 11.216.

Explanation:

Hello there!

In this case, according to the ionization of ammonia in aqueous solution:

NH_3+H_2O\rightleftharpoons NH_4^++OH^-

We can set up its equilibrium expression in terms of x as the reaction extent equal to the concentration of each product at equilibrium:

Kb=\frac{[NH_4^+][OH^-]}{[NH_3]} \\\\1.80x10^{-5}=\frac{x*x}{0.150-x}

However, since Kb<<<1 we can neglect the x on bottom and easily compute it via:

1.80x10^{-5}=\frac{x*x}{0.150}\\\\x=\sqrt{1.80x10^{-5}*0.150}=1.643x10^{-3}M

Which is also:

[OH^-]=1.643x10^{-3}M

Thereafter we can compute the pOH first:

pOH=-log(1.643x10^{-3}M)\\\\pOH=2.784

Finally, the pH turns out:

pH=14-2.784\\\\pH=11.216

Regards!

5 0
3 years ago
At 25.5°C a gas has a volume of 125mL. What would be the volume be if the temperature increased to 50°C
kolezko [41]

Answer:

245 mL

Explanation:

Please see the step-by-step solution in the picture attached below.

Hope this answer can help you. Have a nice day!

7 0
3 years ago
in an experiment 3.5g of element A reacted with 4.0g of element G to form a compound Calculate the empirical formula for this co
kolezko [41]

Additional information

Relative atomic mass(Ar) : A=7, G=16

The empirical formula : A₂G

<h3>Further explanation</h3>

Given

3.5g of element A

4.0g of element G

Required

the empirical formula for this compound

Solution

The empirical formula is the smallest comparison of atoms of compound forming elements.

The empirical formula also shows the simplest mole ratio of the constituent elements of the compound

mol of element A :

\tt mol=\dfrac{mass}{Ar}\\\\mol=\dfrac{3.5}{7}=0.5

mol of element G :

\tt mol=\dfrac{4}{16}=0.25

mol ratio A : G = 0.5 : 0.25 = 2 : 1

4 0
2 years ago
If a certain gas occupies a volume of 10. L when the applied pressure is 5.0 atm , find the pressure when the gas occupies a vol
lorasvet [3.4K]

Answer:

20L is the new volume

Explanation:

In this case, moles and T° from the gas remain constant. This is the formula we must apply, to solve this:

P₁ . V₁ = P₂ . V₂

5 atm . 10 L = P₂ . 2.5L

P₂ = (5 atm . 10 L) / 2.5L →20L

5 0
3 years ago
A plant extract can be obtained with organic solvents such as acetone or ethyl alcohol, and is composed of plant pigments such a
prohojiy [21]

Answer:

Here's what I get  

Explanation:

A plant extract is a mixture because it contains different substances: acetone or ethanol, chlorophylls A and B, carotene and xanthophylls.

It is homogeneous because it is a solution. There is only one phase: the liquid phase. You cannot see the pigments as separate phases.

You can separate the pigments by paper, thin layer, or column chromatography.

Many schools use paper chromatography, because paper is cheap.

As the mixture of pigments follows the solvent up the paper, they separate into different coloured bands according to their attractive forces to the cellulose in the paper.

The chlorophylls are strongly attracted to the paper, so they don't travel very far.

The nonpolar carotene molecules have little attraction to the polar cellulose, so they are carried along by the solvent front.

8 0
3 years ago
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