TIMED ASSIGNMENT

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

In an aqueous solution which substance yields hydrogen ions as the only positive ion *

GenaCL600 [577]

The question is incomplete. Complete question is
In an aqueus solution, which substance yields hydrogen ions as the only positive ions in the solution? 1)NaH 2)HCOOH 3)LiOH 4) CH3CH2OH?
.............................................................................................................................
Answer: Correct answer is option 2, HCOOH

Reason:
HCOOH is a formic acid. When mixed in water, it undergoes dissociation which can be represented as

HCOOH ↔ HCOO- + H+

The compound NaH, will generate hydride ion (H-), while LiOH is an ionic compound, hence when dissolved in water it generated OH- ions. The compound CH3CH2OH is named as ethyl alcohol. This compound donot dissociate in aqueous medium.

7 0

4 years ago

The increase in atomic radius as you go down the periodic table is caused by?

Kryger [21]

Answer: The number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases as the group and energy levels increase.

8 0

3 years ago

Question is in the photo

Sedbober [7]

Percentage composition of a compound is a ratio of an amount of each element to the total amount of individual elements in a compound, which is then multiplied with 100.

5 0

3 years ago

The Ksp for Cu(OH)2 is 4.8 × 10-20. Determine the molar solubility of Cu(OH)2 in a buffer solution with a pH of 10.1.

Papessa [141]

Answer:

E) 3.0x10⁻¹²

Explanation:

Ksp of Cu(OH)₂ is defined as:

Cu(OH)₂(s) ⇄ Cu²⁺(aq) + 2 OH⁻(aq)

Ksp = [Cu²⁺] [OH⁻]²

When pH is 10.1, [OH⁻] is:

pOH = 14 - pH

pOH = 3.9

pOH = -log [OH⁻]

[OH⁻] = 1.26x10⁻⁴M

Replacing in ksp formula:

4.8x10⁻²⁰= [Cu²⁺] [1.26x10⁻⁴]²

3.0x10⁻¹² = [Cu²⁺]

That means the maximum amount of Cu²⁺ that can be in solution is 3.0x10⁻¹²M, thus, molar solubility of Cu(OH)₂ is

E) 3.0x10⁻¹²

3 0

4 years ago