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3 years ago

Question 1: Which of the following is an example of an exothermic chemical reaction?

Chemistry

1 answer:

Allushta [10]3 years ago

5 0

Answer:

the answer is D

Explanation:

the reason how ik this is that i already did this test so yea

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What is the composition of 'Clean dry air'<br><br> - Idk what subject its just science

Luba_88 [7]

Dry air is a mixture of nitrogen, oxygen, carbon dioxide etc.
air is a mixture of gases 78% nitrogen an 21% oxygen and other components.

7 0

3 years ago

A mixture of0.161 moles of C is reacted with 0.117 moles of O2 in a sealed, 10.0 L-vessel at 500.0 K, producing a mixture of CO

labwork [276]

Answer:

number of moles of CO2 is 0.054

number of moles of CO is 0.107

number of moles of O2 remaining is 0.01 mole

mole fraction of CO is 0.63

Explanation:

Firstly, we write the equation of reaction;

3C(s) +2O2(g) → CO2(g) +2CO(g)

Now, we proceed.

From the written equation, we can deduce that

3 mol C = 2 mol O2 = 1 mol CO2 = 2 mol CO

No of mol of C reacted = 0.161 mol

limiting reactant according to the question is Carbon

a. no of mol of CO2 formed = 0.161*1/3 = 0.054 moles ( no of moles of CO2 formed is one-third of no of moles of carbon reacted. This is obtainable from their mole ratio 1:3)

b. no of mol of CO formed = 0.161*2/3 = 0.107 mol

c. no of mol of O2 remaining = 0.117 - (0.151*2/3) = 0.117-0.107 = 0.01 mole

d. mole fraction of CO = no of mol of CO/Total number of moles

= 0.107/(0.107+0.054+0.01)

= 0.625730994152 which is approximately 0.63

5 0

3 years ago

Without doing any calculations, match the following thermodynamic properties with their appropriate numerical sign for the follo

siniylev [52]

Answer:

∆H > 0

∆Srxn <0

∆G >0

∆Suniverse <0

Explanation:

We are informed that the reaction is endothermic. An endothermic reaction is one in which energy is absorbed hence ∆H is positive at all temperatures.

Similarly, absorption of energy leads to a decrease in entropy of the reaction system. Hence the change in entropy of the reaction ∆Sreaction is negative at all temperatures.

The change in free energy for the reaction is positive at all temperatures since ∆S reaction is negative then from ∆G= ∆H - T∆S, we see that given the positive value of ∆H, ∆G must always return a positive value at all temperatures.

Since entropy of the surrounding= - ∆H/T, given that ∆H is positive, ∆S surrounding will be negative at all temperatures. This is so because an endothermic reaction causes the surrounding to cool down.

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3 years ago

Write a balanced equation formed when the following elements react with oxygen:a)Zinc

Ainat [17]

Explanation:

a) when zinc burnt in oxygen.

2Zn + O2 -----∆-----> 2ZnO(black residue)

b) when carbon burnt in oxygen.

C+O2----∆---> CO2.

c) when sulphur burnt in oxygen.

S+O2-----∆-----> SO2.

d) when Calcium burnt in oxygen.

2Ca+O2-----∆-----> 2CaO(black residue)

e) when Magnesium burnt in oxygen.

2Mg+O2-----∆----> 2MgO.

f) when sodium burnt in oxygen.

4Na+O2----∆-----> 2Na2O.

hope all these reactions help you.

4 0

3 years ago

How can the law of conservation of<br> mass for a chemical reaction be expressed?

djverab [1.8K]

Answer:

The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

Explanation:

How does the concept of conservation of mass apply to chemical reactions? the reactants and products have exactly the same atoms. the reactants and products have exactly the same molecules. the change in the amount of matter is equal to the change in energy.

can someone help me with my qustions?

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3 years ago