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3 years ago

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Chemistry

2 answers:

Naddika [18.5K]3 years ago

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Awh, why are you sad? :(

Sloan [31]3 years ago

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Me too hun

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A chemist measures the energy change

Flauer [41]

Answer:

For (1): The correct option is (a)

For (2): The correct option is (a) and 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts.

Explanation:

There are 2 types of reactions that are classified based on enthalpy change:

Endothermic reactions: These are the reactions where heat is absorbed by the reaction. The change in enthalpy of the reaction, $\Delta H_{rxn}$ is positive for these reactions.

Exothermic reactions: These are the reactions where heat is released by the reaction. The change in enthalpy of the reaction, $\Delta H_{rxn}$ is negative for these reactions.

For (1):

For the given chemical reaction:

$2NH_3(g)\rightarrow N_2(g)+3H_2(g);Delta H=160kJ$

As the change in enthalpy or heat of the reaction is positive. Thus, the reaction is an endothermic reaction because heat is absorbed by the reaction.

For (2):

When ammonia reacts, some amount of heat will be absorbed by the reaction. Thus, we can say the heat will be absorbed.

The number of moles is calculated by using the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

Given mass of ammonia = 70.9 g

Molar mass of ammonia = 17 g/mol

Using equation 1:

$\text{Moles of ammonia}=\frac{70.9g}{17g/mol}=4.17mol$

By stoichiometry of the reaction:

If 2 mole of ammonia reacts, the heat absorbed is 160 kJ

So, if 4.17 moles of ammonia reacts, the heat absorbed will be = $\frac{160kJ}{2mol}\times 4.17mol=333.6kJ$

Hence, 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts

8 0

3 years ago

What is the molarity of a solution made from dissolving 3.0 moles of NaCl in 250 mL of solution?

pentagon [3]

Answer:

Molarity = 12 M

Explanation:

Given data:

Molarity of solution = ?

Number of moles of NaCl = 3.0 mol

Volume of solution = 250 mL (250/1000 = 0.25 L)

Solution:

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

Molarity = 3.0 mol / 0.25 L

Molarity = 12 M

7 0

3 years ago

Read 2 more answers

How many moles are in 456 g of CaCO3

GrogVix [38]

Answer:

4.556 moles

Explanation:

mole=mass/ molar mass

mole= 456/100.08

mole= 4.556

3 0

3 years ago

Need help with this question

valentinak56 [21]

The answer is B.

Each of the points or vertex represent a carbon atom. Answer choice B is the only choice that has 8.

6 0

3 years ago

Considering the following precipitation reaction: Pb(NO3)2(aq) + 2Kl(aq) – Pbl (s) + 2KNO3(aq) IN What is the correct complete i

brilliants [131]

Answer:

Pb²++2I−→PbI2(s)

yellow precipitate

Explanation:

6 0

3 years ago

Gift points I'm sad..........​

Gift points I'm sad..........