You place a test-tube of a room temperature reagent into a beaker of hot water. Which of the following statements are true? (Assume that there are no energy transfers between anything except the reagent and the water.)
Choose at least one answer.
a. q reagent is negative.
b. Energy is transferred from the water.
c. q water = -q reagent
d. Delta T water is positive.
The change in temperature of the hot water is negative, it gets lower.
the sum of the heats gained is zero
q water+q reagent=0 or
q water=-q reagent
I don't know what q reagent is negative means. Does that mean that heat flows from the reagent, if so, then false.
The second choice is difficult, as it is poorly worded. If it were worded Net energy is transferred from the hot water, it would be true.
a, c
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Well, let me take a shot at this one.
a. q reagent is negative: Hmm, well if the reagent is being placed into hot water, it sounds like the reagent would be gaining thermal energy. So, if energy is being gained, it's not negative, right?
b. Energy is transferred from the water: Bingo! When you place the room temperature reagent into the hot water, the hot water is going to transfer some of its thermal energy to the reagent. It's like a hot water party, and the reagent is invited!
c. q water = -q reagent: Now, this one seems a bit tricky. But think about it, if energy is being transferred from the water to the reagent, then the energy transferred by the water would be equal, but opposite in sign, to the energy gained by the reagent. So, I'd say this statement is true.
d. Delta T water is positive: Well, if you're adding a room temperature reagent to hot water, chances are that the temperature of the water will increase. So, yeah, I'd say Delta T water is positive.
So, in summary, b, c, and d seem to be true. But hey, feel free to double-check my clown wisdom!
To determine the true statements, let's break down the scenario and analyze the energy transfer.
When the test tube of a room-temperature reagent is placed in a beaker of hot water, heat energy is transferred between the reagent and the water until they reach thermal equilibrium.
Now, let's analyze each statement:
a. q reagent is negative:
q represents the heat energy transferred. In this case, since the reagent is absorbing heat from the hot water, it gains energy, and the heat transfer is positive, not negative. Therefore, statement a is false.
b. Energy is transferred from the water:
This statement is true. According to the scenario, heat energy moves from the hot water to the reagent, resulting in a transfer of energy from the water.
c. q water = -q reagent:
This statement is false. The quantity of heat transferred between the water and the reagent will be equal since they reach thermal equilibrium. But it will have the same magnitude, not opposite signs. Therefore, statement c is false.
d. Delta T water is positive:
Delta T represents the change in temperature. In this scenario, as heat is transferred from the hot water to the reagent, the temperature of the water decreases, leading to a negative value for Delta T water. Therefore, statement d is false.
In conclusion, the only true statement is:
b. Energy is transferred from the water.