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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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3 years ago
How are the following aspects of a reaction affected by the addition of a catalyst? 1) activation energy of the reverse reaction
snow_tiger [21]

These are four questions and four answers.

Answers:

1) activation energy of the reverse reaction

     b. Decreased

2) Rate of the forward reaction

    a. Increased

3) Rate of the reverse reaction

    a. Increased

4) Activation energy of the forward reaction

    b. decreased

Explanation:

<em>Activarion energy</em> is the energy required by the reactants to form the intermediate transition state and become products.

<em>Catalysts</em> are substances that change the path of the chemical reactions, lowering the activation energy, and thus speeding up the rate of the reactions, since the products can reach the new lower activation energy faster.

The equilibrium reactions are the chemical process in which two reactions, the <em>forward and the reverese reactions</em>, occur simultaneously and at the same rate.  The equlibrium reactions may be represented by:

  • A ⇄ B

Where A → B is the direct or forward reaction, and A ← B is the reverse reaction (note the inversed arrow, from right to left).

For the direct reaction A represents the reactants and B represents the products. On the other hand, B represents the reactants and A represents the reactants of the reverse reaction and A. This, is A is the reactant of the forward reaction and the product of the reverse reaction, while B is the reactant of the reverse reaction and the product of the forward reaction.

Since, <em>the addition of a catalyst</em> lowers the activation energy of the process, the new activation energy is lower for both the forward and the reverse reaction, meaning that:

1. <em>The activation energy of the reverse reaction is decreased</em> (option b. of the first question)

2.<em> The rate of the forward reaction is increased</em> (option a. of the second question)

3. <em>The rate of the reverse reaction is increased</em> (option a. of the third question).

4. <em>Activation energy of the forward reaction is decreased</em> (option b. of the fourth question).

In summary, the addition of a catalyst decreases the activation energy for both forward and reverse reactions, and increases the rate of both forward and reverse reactions.

3 0
3 years ago
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anzhelika [568]

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zavuch27 [327]

Answer:

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