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3 years ago

In the chemical reaction below, calcium (Ca) and water (H2O) react to form calcium hydroxide (Ca(OH)2) and hydrogen gas (H2).

Chemistry

1 answer:

shtirl [24]3 years ago

5 0

C
because the mass never changes, it is always equal on both sides.

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The value of ΔH for the reaction below is -72 kJ. __________ kJ of heat are released when 1.0 mol of HBr is formed in this react

eimsori [14]

Answer:

36 KJ of heat are released when 1.0 mole of HBr is formed.

Explanation:

By Hess law,

The heat of any reaction ΔH for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction:

H 2 (g) + Br 2 (g) → 2HBr (g) ΔH = -72 KJ

This is the energy released when 2 moles of HBr is formed from one mole each of H2 and Br2.

Therefore, Heat released for the formation of 1 mol HBr would be half of this.

Hence,

ΔHreq = -36 kJ

36 KJ of heat are released when 1.0 mole of HBr is formed.

4 0

3 years ago

How many moles of co2 are produced when 5.40 mol of ethane are burned in an excess of oxygen?

Nimfa-mama [501]

Reaction of ethane combustion:

2C2H6 (g) + 7O2 (g) ----> 4CO2 (g) + 6H2O

According to the reaction, we can see that C2H6 and CO2 have following stoichiometric ratio:

n(C2H6) : n(CO2) = 2 : 4

If we know the number of moles of ethane we can calculate moles of carbon dioxide:

2 x n(CO2) = 4 x n(C2H6)

n(CO2) = 2 x n(C2H6)

n(CO2) = 2 x 5.4 = 10.8 mole of CO2 are produced

3 0

4 years ago

What is the percentage yield of O2 if 12.3 g of KClO3 (molar mass 123 g) is decomposed to produce 3.2 g of O2 (molar mass 32 g)

My name is Ann [436]

Answer:

The percentage yield of O2 is 66.7%

Explanation:

Reaction for decomposition of potassium chlorate is:

2KClO₃ → 2KCl + 3O₂

The products are potassium chloride and oxygen.

Let's find out the moles of chlorate.

Mass / Molar mass = Moles

12.3 g / 123 g/mol = 0.1 mol

So ratio is 2:3, 2 moles of chlorate produce 3 mol of oxygen.

Then, 0.1 mol of chlorate may produce (0.1 .3)/ 2 = 0.15 moles

Let's convert the moles of produced oxygen, as to find out the theoretical yield.

0.15 mol . 32 g/ 1mol = 4.8 g

To calculate the percentage yield, the formula is

(Produced Yield / Theoretical yield) . 100 =

(3.2g / 4.8g) . 100 = 66.7 %

8 0

4 years ago

Ty thinks it's strange that a person with an Asian-sounding name speaks Spanish as her primary language. Ty's thoughts are an ex

Aliun [14]

The correct answer is c

6 0

3 years ago

Do objects that give off light often give off heat?

pashok25 [27]

Answer:

Yes

Explanation:

Thermal radiation is emitted by any surface having a temperature higher than absolute zero. So the short answer to your question is yes. Light (electromagnetic radiation) of any frequency will heat surfaces that absorb it.

I hope it helps.

3 0

3 years ago

Read 2 more answers