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3 years ago

The estimate obtained from a sample of which size is likely to be closest to

Chemistry

2 answers:

zubka84 [21]3 years ago

8 0

The answer is C, 85.

Leokris [45]3 years ago

5 0

the closest value is C, 85.

hope it helps!!!!

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A student dissolves 15.0 g of ammonium chloride(NH4Cl) in 250. 0 g of water in a well-insulated open cup. She then observes the

iren2701 [21]

Answer:

1) Endothermic.

2) $Q_{rxn}=4435.04J$

3) $\Delta _rH=15.8kJ/mol$

Explanation:

Hello there!

1) In this case, for these calorimetry problems, we can realize that since the temperature decreases the reaction is endothermic because it is absorbing heat from the solution, that is why the temperature goes from 22.00 °C to 16.0°C.

2) Now, for the total heat released by the reaction, we first need to assume that all of it is released 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:

$Q_{rxn}=-(15.0g+250.0g)*4.184\frac{J}{g\°C}(16.0-20.0)\°C\\\\ Q_{rxn}=4435.04J$

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 NH4Cl, we proceed as follows:

$\Delta _rH=\frac{ Q_{rxn}}{n}\\\\\Delta _rH= \frac{ 4435.04J}{15.0g*\frac{1mol}{53.49g} } *\frac{1kJ}{1000J} \\\\\Delta _rH=15.8kJ/mol$

Best regards!

4 0

3 years ago

Quarks are<br> A A Fact<br> B Fiction<br> C Both of the above<br> D Neither of the above

stiks02 [169]

I’d say A. They are theoretical in the fact that they have not been observed directly, but have been confirmed to exist through experimentation.

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3 years ago

A buffer solution is prepared by dissolving equal amounts of ascorbic acid and sodium ascorbate, the conjugate base, in water. T

Gnom [1K]

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2 years ago

If the density of water is 1g/ml, what is the mass of 254ml of water?

Mariulka [41]

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