Edge2020 Need Help

Select True or False from the pull down menus for the following statements.

Shkiper50 [21]

Answer:

First question: 1- False, 2- True, 3- False, 4 -Tue, 5- True.

Second question: 12.7 ºC

Explanation:

First question:

1- When a phase change for a pure substance is taking place under constant pressure, the temperature remains constant, and there's no sensitive heat flowing, but there's latent heat flow, which must be added to separate the molecules and to increase the kinetic energy.

2- When observed the heating and the cooling curve, at the phase change, there is no change in temperature, so it must be a horizontal line, which has a slope equal to 0.

3- Heat is the energy that is transferred by the substances or bodies because of a difference in temperature. The temperature is the measure of average kinetic energy in the molecules, so they are different.

4- As explained above, it's true, that's the definition of temperature.

5- Melting and freezing are the opposite processes and they occur at the same temperature. The difference is that for melting, the substance is absorbing heat, and for freezing it is losing heat, but the heat amount is the same for both process and is calculated by Q = ±m*L, where Q is the heat, m the mass, L the heat capacity, and the signal ± indicates if the substance is absorbing (+) or losing (-) heat.

Second question:

For the conservation of energy, the total amount of heat must be 0. The coin is losing heat, so it must be negative. The water is gaining heat, so it must be positive:

Qw - Qc = 0

Q = m*s*ΔT, where Q is the heat, m is the mass, s is the specif heat, and ΔT the temperature variation (final - initial). Qw is from water and Qc for the coin. The specif heat from the water is 4.184 J/gºC. At the thermal equilibrium, the final temperature must be equal for both.

mw*sw*ΔTw = mc*sc*ΔTc, if the coin is pure silver, sc = 0.233 J/gºC

27.0*4.184*(T - 15.5) = 15.5*0.233*(T - 100)

112.968*(T - 15.5) = 3.6115*(T - 100)

112.968T - 1751.004 = 3.6115T - 361.15

109.3565T = 1389.854

T = 1389.854/109.3565

T = 12.7ºC

So, the final water temperature would be 12.7ºC, which is impossible because it needs to increase. So the coin is not silver pure.

7 0

3 years ago

What should each experiment only have one of?

Ket [755]

Answer: varriable

Explanation:meaning one element, feature or factor able to change

3 0

3 years ago

Write a chemical equation for the reaction that occurs in the following cell: Cu|Cu2+(aq)||Ag+(aq)|Ag. Of the two metals, copper

KatRina [158]

Answer:

Answer is given below.

Explanation:

Anode is that electrode where oxidation occurs. Cathode is that electrode where reduction occurs.

In cell representation, half cell present left to salt-bridge notation $(\parallel )$ is anodic system and another half cell present right to salt-bridge notation $(\parallel )$ is cathodic system.

So anode is Cu and cathode is Ag.

oxidation: $Cu-2e^{-}\rightarrow Cu^{2+}(aq.)$

[reduction: $Ag^{+}+e^{-}\rightarrow Ag$ ] $\times 2$

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chemical equation: $Cu+2Ag^{+}(aq.)\rightarrow Cu^{2+}(aq.)+2Ag$

Oxidizing agent is that species which takes electron from another species. Here $Ag^{+}(aq.)$ takes electron from Cu. Hence $Ag^{+}(aq.)$ is the oxidizing agent.

Reducing agent is that species which gives electron to another species. Here Cu gives electron to $Ag^{+}(aq.)$ . Hence Cu is the reducing agent.

6 0

3 years ago

Which of these correctly describes the energy that makes the carousel turn

Dmitrij [34]

Answer:

F

Explanation:

A carousel can be made to rotate using different sources of energy. One may decide to use electric energy, manual effort, water energy or heat energy as in a candle carousel.

When the candle is lit, heat energy is supplied and warm air rises heating up the air near the carousel eventually causing it to start rotating.

Hence heat from the candle leads to a current of warm air that rises up, causing the carousel to start rotating.

8 0

3 years ago

3 attempts left Check my work Click in the answer box to activate the palette. Write the balanced chemical equation where liquid

mel-nik [20]

Answer:

2 C₄H₁₀(l) + 13 O₂(g) ⇄ 8 CO₂(g) + 10 H₂O(g)

Explanation:

When a substance burns we talk about a combustion reaction. When combustion is complete the products are carbon dioxide and water, like in this case. The equation is:

C₄H₁₀(l) + O₂(g) ⇄ CO₂(g) + H₂O(g)

First, we balance the element with the largest stoichiometric coefficient (C).

C₄H₁₀(l) + O₂(g) ⇄ 4 CO₂(g) + H₂O(g)

Then, we balance H because it is in just 1 compound on each side.

C₄H₁₀(l) + O₂(g) ⇄ 4 CO₂(g) + 5 H₂O(g)

Finally, we balance O.

C₄H₁₀(l) + 6.5 O₂(g) ⇄ 4 CO₂(g) + 5 H₂O(g)

Since we want the smallest whole numbers, we multiply all coefficients by 2.

2 C₄H₁₀(l) + 13 O₂(g) ⇄ 8 CO₂(g) + 10 H₂O(g)

4 0

3 years ago