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3 years ago

Express the answers to these problems in the correct number of

Chemistry

1 answer:

timama [110]3 years ago

7 0

Answer:

I solved the questions then counted how many significant figures in each answer

eg,

0.042m+1.33m =1.372m

1.372 has 4 significant figures

that's how you do others

Explanation:

6. 1.372m = 4 significant figures

7. 4.345g = 4 significant figures

8. 12L = 2 significant figures

9. 27.3cm = 3 significant figures

10. 0.975 = 3 significant figures

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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 chemical formulas represents oxygen gas??

lesantik [10]

It is O with a little 2 subscript. it represents two atoms of oxygen.

5 0

3 years ago

Read 2 more answers

Consider the above reaction using 25.0 mL of tert-butyl alcohol (d = 0.786 g/mL) with 60.0 mL of concentrated hydrobromic acid (

Liono4ka [1.6K]

Answer:

Theoretical yield: 36,3g

Percent yield: 71,9%

Explanation:

The reaction of tert-butyl alcohol with hydrobromic acid to produce tert-butyl bromide is a 1:1 reaction.

Moles of tert-butyl alcohol in 25,0 mL are:

25,0mL × (0,786g / mL) × (1mol / 74,12g) = 0,265 moles of tert-butyl alcohol

Moles of hydrobromic acid are:

60,0mL× 47,0% × (1,49g / mL) × (1mol / 80,91g) = 0,519 moles of HBr

As moles of tert-butyl alcohol are less than moles of HBr, limiting reactant is tert-butyl alcohol.

Theoretical yield of tert-butyl bromide in grams is:

0,265 moles × (137,02g / 1mol) = 36,3g

Percent yield:

26,1g / 36,3g × 100 = 71,9%

The reactions are in the image.

There are many ways to produce alkyl halides from primary and secondary alcohols. The reaction in this case is the Appel reaction.

The reaction of tertiary alkyl halides may undergo a hydrolysis reaction -under proper conditions- to form an alcohol and a hydrogen halide.

I hope it helps!

5 0

4 years ago

Which type of bond is found between atoms of solid cobalt?

Vsevolod [243]

The answer is (3) metallic. Cobalt is a transition metal, so it can't be covalent bonds, which bond non-metals, therefore eliminating choice 1 and 2. Ionic bonds are between metals and non metals, but solid cobalt does not have a non metal, eliminating choice 4 as well. Metallic bonds are bonds between metals, therefore the answer is (3) metallic.

3 0

4 years ago

Read 2 more answers

What is the empirical formula of a compound that contains only iron and oxygen and is 22.27% oxygen?

8090 [49]

Answer:

A) FeO

Explanation:

Options:

A) FeO

B) FeO2

C) Fe2O

D) Fe7O2

The correct answer is A) FeO.

(Hope this helps can I pls have brainlist (crown)☺️)

6 0

3 years ago