4K + O2 + 2K20 Which statement is true?

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:

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

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4 0

3 years ago

Write a conclusion using the CER method. Your conclusion must include the following: - Claim: State your claim. Your claim is th

Karolina [17]

Nobody on here is going to write a entire cer for you

4 0

3 years ago

Calculate the ph of sweater which has a hydrogen ion concentration of 1 times 10 to the power of 8

telo118 [61]

Answer:

The pH of the sweater containing Hydrogen ion concentration

$[H^{+}]=1\times 10^{-8}$ is

8

Explanation:

pH = It is the negative logarithm of activity (concentration) of hydrogen ions.

pH = -log([H+])

Now, In the question the concentration of [H+] ions is :

$[H^{+}]=1\times 10^{-8}$

$pH = -log(1\times 10^{-8})$

use the relation:

$log(10^{-a})=a$

$pH= -(-8)$

pH = 8

Note : 1 times 10 to the power of 8 must be" 1 times 10 to the power of -8"

If the concentration is

$[H^{+}]=1\times 10^{8}$

Then pH = -8 , which is not possible . So in that case the pH calculation is by other method

5 0

3 years ago

Calcium chloride is added to the roadways after a snowstorm. Which colligative property is being showcased here?

vlabodo [156]

Answer:

Option (D) freezing point depression

Explanation:

Calcium chloride is added to the roadways after a snowstorm because it reduces the freezing point of the ice. Further more, it has been observed that the calcium chloride also produces enough heat which enhances the melting of the ice as it produces an exothermic reaction.

6 0

3 years ago

How many grams of aluminum will be deposited by 0.1F? (Al=27) a.0.3g b. 0.9. c. 9.0g. d. 2.7g

andrezito [222]

Based on the charge on the aluminium ion, 0.9 g of aluminium are deposited by 0.1 F of electricity.

<h3>What is electrolysis?</h3>

Electrolysis is the decomposition of a substance known as an electrolyte when electric current is passed through it.

The mass and hence moles an electrolyte deposited when current is passed through it depends on the charge on the ion.

Aluminium ion has a charge of +3 and requires 3F of electricity to deposit 1 mole or 27 g of aluminium

0.1 F will discharge = 0.1/3 × 27 g of aluminium

mass of aluminium deposited = 0.9 g of aluminium.

Therefore, 0.9 g of aluminium are deposited by 0.1 F of electricity.

Learn more about electrolysis at: brainly.com/question/26050361

5 0

2 years ago