Answer:
o The result of a chemical change is a different composition; in a physical change, the composition remains the same.
Explanation:
In a chemical change, new kinds of matter are produced although the atoms are the same.
For physical changes, no new kinds of matter formed. Only the state of substances changes.
- Most chemical changes are usually irreversible
- Physical changes are reversible in most parts.
- Changes in state and form are salient characteristics of physical changes.
- When new products are formed from the reactants, it is an indicator of a chemical change.
Answer:
Explanation:
Here the total force at the horizontal components will be equal to the centripetal force on the car. So we will have:
(1)
- f(fr) is the friction force
- N is the normal force
Now, the sum of forces at the vertical direction is equal to 0.
(2)
Let's combine (1) and (2) to find f(fr)
I hope it helps you!
<span>They are balanced. If the forces were not balanced the book would move*. In this example, the downward force of gravity on the book is counterbalanced by the upthrust of the desk. </span>
Explanation:
Exothermic reaction is defined as the reaction in which release of heat takes place. This also means that in an exothermic reaction, bond energies of reactants is less than the bond energies of products.
Hence, difference between the energies between the reactants and products releases as heat and therefore, enthalpy of the system will decrease.
Whereas in an endothermic reaction, heat is supplied from outside and absorbed by the reactant molecules. Hence, enthalpy of the system increases.
As water acts as a coolent and when fuel rods in a nuclear reactor are immersed in it then heat created by coolent is absorbed by water and then it changes into steam.
Since, absorption of heat occurs in the nuclear reactor. Therefore, it is an endothermic reaction.
Thus, we can conclude that nuclear reactors use fuel rods to heat water and generate steam. This process is endothermic.
Answer:
ΔU = - 310.6 J (negative sign indicates decrease in internal energy)
W = 810.6 J
Explanation:
a.
Using first law of thermodynamics:
Q = ΔU + W
where,
Q = Heat Absorbed = 500 J
ΔU = Change in Internal Energy of Gas = ?
W = Work Done = PΔV =
P = Pressure = 2 atm = 202650 Pa
ΔV = Change in Volume = 10 L - 6 L = 4 L = 0.004 m³
Therefore,
Q = ΔU + PΔV
500 J = ΔU + (202650 Pa)(0.004 m³)
ΔU = 500 J - 810.6 J
<u>ΔU = - 310.6 J (negative sign indicates decrease in internal energy)</u>
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b.
The work done can be simply calculated as:
W = PΔV
W = (202650 Pa)(0.004 m³)
<u>W = 810.6 J</u>
