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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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A military jet cruising at an altitude of 12.0kmand speed of 1900./kmh burns fuel at the rate of 74.4/Lmin. How would you calcul
anygoal [31]

Answer: amount = 2466.95L

Explanation:

given that the speed is = 1900./kmh i.e. 1hr/900km

distance = 1050km

the fuel burns at a rate of 74.4 L/min

therefore the amount of fuel that the jet consumes on a 1050.km becomes;

total fuel used = time × fuel burning rate

where time = distance / speed

∴ total fuel used (consumed) = time × fuel burning rate

total fuel consumed = (1050km × 1hr/1900km) × (60min/ 1hr × 74.4L/1min)

total fuel consumed = 2466.95L

6 0
3 years ago
On earth, hydrogen and helium are naturally found as gases. Why are they liquid on the outer planets?
Valentin [98]
<span>The outer layers of the planet are gas. Deeper within the planet, pressure compresses the gases into a liquid. Some evidence suggests that Jupiter may have a small rocky core at its center.</span>
8 0
3 years ago
How many half-lives are required for three-fourths of the nuclei of an isotope in a sample to decay?
prisoha [69]
2 half lives are required.
5 0
3 years ago
Will the calculated Molarity of NaOH be too high or too low or unaffected if the following happen: when you answer the question,
vodomira [7]

Answer:

Explanation:

The result will be affected.

The mass of KHP  weighed out was used to calculate the moles of KHP weighed out (moles = mass/molar mass).

Not all the sample is actually KHP if the KHP is a little moist, so when mass was used to determine the moles of KHP, a higher number of moles than what is actually present would be obtained (because some of that mass was not KHP but it was assumed to be so. Therefore, there is actually a less present number of moles than the certain number that was thought of.

During the titration, NaOH reacts in a 1:1 ratio with KHP. So it was determined that there was the same number of moles of NaOH was the volume used as there were KHP in the mass that was weighed out. Since there was an overestimation in the moles of KHP, then there also would be an overestimation in the number of moles of NaOH.

Thus, NaOH will appear at a higher concentration than it actually is.

7 0
3 years ago
Physical and chemical properties of a piece of cooked chicken and a glass of kool-aid
Lunna [17]
A cooked chicken would be somewhat burnt or cooked. A glass of kool aid would be mixed, or aka homogenous mixture. The glass would maintain a color, because its not water. 
6 0
3 years ago
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