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S_A_V [24]
3 years ago
13

Which statements are true?

Chemistry
1 answer:
schepotkina [342]3 years ago
5 0

Explanation:

  • Evaporation is defined as a process in which liquid state of water is changing into vapor state.

So, we need to break the bonds of liquid substance in order to convert it into vapor state. And, energy is absorbed for breaking of bonds which means that evaporation is an endothermic process.

Hence, the statement evaporation of water is an exothermic process is false.

  • When a hydrocarbon reacts with oxygen and leads to the formation of carbon dioxide and water then this type of reaction is known as combustion reaction.

A combustion reaction will always release heat energy. Hence, combustion reaction is exothermic in nature.

  • When energy is transferred as heat from the surroundings to the system then it means energy is being absorbed by the system. And, absorption of heat is an endothermic process for which \Delta H is positive.
  • Whereas when energy is transferred from system to the surrounding then it means energy is released by the system which is an exothermic process.

Hence, for an exothermic process value of \Delta H is negative.

Thus, we can conclude that statements which are true are as follows.

  • A combustion reaction is exothermic.
  • When energy is transferred as heat from the system to the surroundings, \Delta H is negative.
  • For an endothermic reaction Deta H is positive.
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4.00 moles of CU(CN)2<br><br>Find the number of grams ​
UNO [17]

Hey there!

Cu(CN)₂

Find the molar mass.

Cu: 1 x 63.546 = 63.546

C: 2 x 12.01 = 24.02

N: 2 x 14.07 = 28.14

-----------------------------------

                      115.706 grams

The mass of one mole of Cu(CN)₂ is 115.706 grams.

We have 4 moles.

115.706 x 4 = 463

4.00 moles of Cu(CN)₂ has a mass of 463 grams.

Hope this helps!

6 0
2 years ago
What is the molality of a solution that contains 1.34 moles of NaCl in 2.47 kg of solvent
dsp73

The molality is 0.54 M when 1.34 moles of NaCl is present in 2.47 kg of solvent.

<u>Explanation:</u>

Molality is the measure of how much of amount of solute is dissolved in the solvent. So it is calculated as the ratio of moles of solute to the grams of solvent.

         \text {Molality}=\frac{\text {Moles of solute}}{\text {Mass of solvent}}

As in this case, the solute is NaCl and solvent is unknown. So the moles of solute is given as 1.34 moles and the mass of solvent is given as 2.47 kg.

Hence, \text { molality }=\frac{1.34}{2.47}= 0.54 \mathrm{M}

Thus, the molality is 0.54 M when 1.34 moles of NaCl is present in 2.47 kg of solvent.

8 0
3 years ago
The process by which particles in a solution spread out evenly is called?
padilas [110]

Answer:

this is your answer.....

7 0
3 years ago
Pls help me <br><br> What is the mass in grams of 2.64 mol of sulfur dioxide, SO2?
notsponge [240]

Answer: The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles SO2, or 64.0638 grams.

Hope it helps.

8 0
2 years ago
An alkanol contains 37.5 carbon
kow [346]

Answer:

Empirical formula is CH₄

Molecular formula = C₂H₈

Explanation:

Mass of carbon = 37.5 g

Mass of hydrogen = 12.5 g

Molecular weight = 32 g/mol

Molecular formula = ?

Empirical formula = ?

Solution:

Number of gram atoms of C = 37.5 g /12g/mol = 3.125

Number of gram atoms of H = 12.5 g / 1.008 g/mol= 12.4

Atomic ratio:

C                 :            H            

3.125/3.125   :       12.4 /3.125

    1                :            4          

C : H : = 1 : 4

Empirical formula is CH₄

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

n = 32  / 16

n = 2

Molecular formula = n (empirical formula)

Molecular formula = 2 ( CH₄)

Molecular formula = C₂H₈

3 0
3 years ago
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