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Sav [38]
3 years ago
12

An unknown substance undergoes a chemical change that gives off heat. What can you tell me about this substance?

Chemistry
2 answers:
marin [14]3 years ago
7 0
On a molecular level there is a lot of movement which in turn is the reason why heat is generated.
madam [21]3 years ago
3 0

Explanation:

A chemical reaction in which heat is absorbed by the reactant molecules is known as an endothermic reaction.

For example, A + B + Heat \rightarrow AB

On the other hand, a chemical reaction in which heat energy is released by the reactant molecules is known as an exothermic reaction.

For example, A + B \rightarrow AB + Heat

Thus, we can conclude that when an unknown substance undergoes a chemical change that gives off heat then it means earlier the substance has more heat energy but after the chemical change there occurs a decrease in its heat energy because some of the heat has been released by it.

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describe in general terms an experiment to determine the molal freezing point depression constant kf of water. Assume the availa
Dvinal [7]
A solution (in this experiment solution of NaNO₃) freezes at a lower temperature than does the pure solvent (deionized water). The higher the solute concentration (sodium nitrate), freezing point depression of the solution will be greater.
Equation describing the change in freezing point: 
ΔT = Kf · b · i.
ΔT - temperature change from pure solvent to solution.
Kf - the molal freezing point depression constant.
b -  molality (moles of solute per kilogram of solvent).
i - Van’t Hoff Factor.
First measure freezing point of pure solvent (deionized water). Than make solutions of NaNO₃ with different molality and measure separately their freezing points. Use equation to calculate Kf.

6 0
2 years ago
In which situation is the object experiencing unbalanced forces?
olga2289 [7]

The moving car experiences unbalanced forces when applying brakes; when a car is slowing as it reaches a stop light.

<h3><u> Explanation: </u></h3>

When the car driver applies brakes to a car in order to stop, an unbalanced force is applied to the car. The speed of car gradually reduces and there’s a decrease in acceleration; a net force acts on it.

Options A and D has a box and a rocket always in a rest position. A car with cruise control is an adaptable speed setting for a vehicle which helps it to maintain a fairly constant speed. Constant velocity gives zero acceleration and hence no considerable unbalanced forces appear.

8 0
2 years ago
Read 2 more answers
Which bond is broken when energy is released?
blsea [12.9K]
Energy is released when a new bonds form.
4 0
3 years ago
Read 2 more answers
Which properties change the composition of a substance?
Elanso [62]

Answer:

A.

Explanation:

Physical properties are characteristics of a substance that can be observed or measured without changing the composition of the substance. Some examples of physical properties are its volume and its density. There are two types of physical properties, intensive physical properties and extensive physical properties.

4 0
3 years ago
Answer ASAP please!!!!!!
Oksi-84 [34.3K]

Answer:

They fall slower.

Explanation:

moon's gravitation force is effected by the mass of the moon

but because the moon has less mass,

objects fall slower because it has less gravitation force

________________________________________________

Hope this helped.

3 0
1 year ago
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