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tiny-mole [99]
3 years ago
7

Does his model correctly show why the properties of the ending substances are different from the properties of the starting subs

tances? Describe what could be correct or incorrect about his model.
Chemistry
1 answer:
topjm [15]3 years ago
6 0

Answer:

Samira's model is incorrect because not all atoms are accounted for

Explanation:

The image of Samira's model has been attached to this answer to enhance the explanation.

What is depicted in that model is rightly regarded as a chemical change. In a chemical change atoms of substances are rearranged as new substances are formed.

However, all atoms in the products must also be found in at least one of the reactants. In this case we have an atom in one of the products that is not accounted for. Hence the model is incorrect.

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A student dissolves 10.7 g of lithium chloride (LiCl) in 300. g of water in a well-insulated open cup. He then observes the temp
Novosadov [1.4K]

Answer:

1) Exothermic.

2) Q_{rxn}=-8580J

3) \Delta _rH=-121.0kJ/mol

Explanation:

Hello there!

1) In this case, for these calorimetry problems, we can realize that since the temperature increases the reaction is exothermic because it is releasing heat to solution, that is why the temperature goes from 22.0 °C to 28.6 °C.

2) Now, for the total heat released by the reaction, we first need to assume that all of it is absorbed by the solution since it is possible to assume that the calorimeter is perfectly isolated. In such a way, it is also valid to assume that the specific heat of the solution is 4.184 J/(g°C) as it is mostly water, therefore, the heat released by the reaction is:

Q_{rxn}=-m_{Total}C(T_2-T_1)\\\\Q_{rxn}=-(300g+10.7g)*4.184 \frac{J}{g\°C} (28.6\°C-22.0\°C)\\\\Q_{rxn}=-8580J

3) Finally, since the enthalpy of reaction is calculated by dividing the heat released by the reaction over the moles of the solute, in this case LiCl, we proceed as follows:

\Delta _rH=\frac{Q_{rxn}}{n_{LiCl}} \\\\\Delta _rH=\frac{-8580J}{10.7g*\frac{1mol}{150.91g} }*\frac{1kJ}{1000J}  \\\\\Delta _rH=-121.0kJ/mol

Best regards!

8 0
3 years ago
A tennis ball could be used to represent the Sun because it is round and yellow. Which of these other things could also be a goo
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Answer:

A

Explanation:

It shines bright just like the sun hopes this helps

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Answer:

Explanation:

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