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nirvana33 [79]
4 years ago
11

Which of the following is NOT an example of a chemical reaction

Chemistry
1 answer:
Charra [1.4K]4 years ago
8 0
D water evaporating it is a physical change
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The gas in a cylinder has a volume of 8 liters at a pressure of 101 kPa. The pressure of the gas is increased to 206 kPa. Assumi
Arlecino [84]
The pressure of the gas is increased<span> to 224 </span><span>kPa</span>
3 0
3 years ago
Predict whether the changes in enthalpy, entropy, and free energy will be positive or negative for the freezing of water, and ex
Dafna11 [192]

Answer:

Explanation:

The total energy or intrinsic energy of a system is called the enthalpy. In thermochemistry, we have two types of enthalpy changes which are:

  • Exothermic changes
  • Endothermic changes

For the freezing of water, the enthalpy change is an exothermic one. Exothermic changes are designated as negative. In this chemical change, heat is liberated to the surroundings and this leaves the environment at a much higher temperature. In freezing, the enviroment gains more heat as the material begins to cool to lower temperature.

Entropy is the degree of randomness or disorderliness of a system. When a phase change occurs from liquid to solid, freezing takes place. Such a change increases the orderliness of a system and entropy diminishes. Here, entropy is negative.

The free energy is a measure of the energy a system that does useful work. Free energy depends on enthalpy, entropy and temperature of a system. For phase changes such as freezing of water, the value of free energy change is 0.

For this process, an increases in temperature makes it non-spontaneous. Increasing temperature would alter the course of the reaction and makes it exothermic. For entropy, increasing temperature would increase entropy and therefore, the reaction would not be feasible.

Temperature would mostly affect the free energy. An increase in temperature would increase the value of entropy change and the reaction would not be spontaneous. With falling temperature value, the reaction becomes more spontaneous and favored.

8 0
3 years ago
Spell out the full name of the compound.
Natalka [10]

Explanation:

Step one look for the longest chain of carbon atoms

Longest chain is 7 C atoms

Step 2 look for double bonds or others functional groups

it is present in 3rd carbon

Therefore IUPAC name is 3-heptene

From point of stereochemistry it can also be written as trans-3-heptene as the hydrogens are placed in opposite side of the C=C bond.

Hope this helps...

3 0
4 years ago
Why does every chemical reaction require a certain amount of activation energy
attashe74 [19]

Every chemical reaction requires a minimum amount of energy to undergo reaction.

The total energy required is Threshold energy. The chemicals have some internal energy and they require some extra energy which is known as activation energy.

The reaction occurs when two molecules or atoms come closer to each other and for this they need kinetic energy.

Now for an effective collision the two molecules or atoms should collide with a minimum amount of energy so that they may undergo reaction so again they need some energy

These kinetic energy and energy for effective collision is actually called as activation energy.

5 0
3 years ago
What is the number of moles of potassium chloride present in 148 g of kcl?
OLga [1]
The number of moles of one substance given the amount in mass can be calculated by the use of the molar mass. This is the mass of a compound per 1 mol of the said substance. For, KCl the molar mass is 74.55 g/ mol

148 g / 74.55 g/mol = 2 mol KCl

Hope this answers the question. have a nice day.
3 0
3 years ago
Read 2 more answers
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