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3 years ago

Match the following associations.

Chemistry

1 answer:

LuckyWell [14K]3 years ago

7 0

Answer:

Here's what I get

Explanation:

$\begin{array}{lcl}\text{1. E2 $$ E1} & = & \text{energy change in an endothermic reaction}\\\text{3. $\Delta$H} & = & \text{symbol for change in energy}\\\text{4. Joule} & = & \text{SI unit of energy}\\\end{array}$

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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

How many molecules are present in 936 g of glucose (C6H12O6)?

tino4ka555 [31]

The Answer would be A. 3.14*1024 molecules.

4 0

3 years ago

Read 2 more answers

A certain substance X has a normal freezing point of -10.1 degree C and a molal freezing point depression constant Kf = 5.32 °C.

Citrus2011 [14]

Answer : The freezing point of a solution is $-15.4^oC$

Explanation : Given,

Molal-freezing-point-depression constant $(K_f)$ = $5.32^oC/m$

Mass of urea (solute) = 29.82 g

Mass of solvent = 500 g = 0.500 kg

Molar mass of urea = 60.06 g/mole

Formula used :

$\Delta T_f=i\times K_f\times m\\\\T^o-T_s=i\times K_f\times\frac{\text{Mass of urea}}{\text{Molar mass of urea}\times \text{Mass of solvent in Kg}}$

where,

$\Delta T_f$ = change in freezing point

$\Delta T_s$ = freezing point of solution = ?

$\Delta T^o$ = freezing point of solvent = $-10.1^oC$

i = Van't Hoff factor = 1 (for urea non-electrolyte)

$K_f$ = freezing point constant = $5.32^oC/m$

m = molality

Now put all the given values in this formula, we get

$-10.1^oC-T_s=1\times (5.32^oC/m)\times \frac{29.82g}{60.06g/mol\times 0.500kg}$

$T_s=-15.4^oC$

Therefore, the freezing point of a solution is $-15.4^oC$

5 0

3 years ago

Mendeleev used his periodic table of elements to

pishuonlain [190]

Mendeleev realized that the physical and chemical properties of elements were related to their atomic mass in a 'periodic' way, and arranged them so that groups of elements with similar properties fell into vertical columns in his table.
Mendeleev rewrote each edition of Principles of Chemistry, including all new scientific data-particularly confirmations of the periodic law-and reanalyzing difficulties that had arisen to hinder its confirmation (inert gases, radioactivity, radioactive and rare-earth elements)
he wanted to prove that he was right.

7 0

3 years ago

What volume does 4.24g of argon gas occupy at 58.2 degrees celcuis and 1528torr

Radda [10]

The volume occupied by the argon gas is, 1.44 L

Explanation :

To calculate the volume of argon gas we are using ideal gas equation:

$PV=nRT\\\\PV=\frac{w}{M}RT$