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Citrus2011 [14]
4 years ago
10

A. An endothermic reaction i taking place in a test tube. What would you expect to feel when you touch the outside of the test t

ube?
b. Identify each of the following changes as either exothermic or endothermic.

- Burning a candle
- Lighting a gas stove
- Using an instant cold pack
- Running a car's engine

c. On the potential energy diagram below, label the reactants and products. Does the diagram shown an endothermic reaction or an exothermic reaction? Write one or two sentences explaining your answer.

Physics
2 answers:
inessss [21]4 years ago
6 0

Explanation:

An endothermic reaction is a type of of chemical reaction in which energy is absorbed from the surrounding. The temperature of the surrounding decreases.

An Exothermic reaction is a type of of chemical reaction in which energy is released into the surrounding. The temperature of the surrounding increases.

a)When an endothermic reaction takes place in test tube the temperature of the surrounding(here the outside wall of the test tube) will decrease which can be felt by touching the outside of the test tube.

b) Burning a candle

,Lighting a gas stove and running a car's engine all are example of exothermic reaction because energy is releases into surroundings. Where as using an instant cold pack is an example endothermic reaction in which energy is absorbed from the surrounding.

c) The diagram is of an exothermic reaction because the energy of the reactants is higher than the energy of the products.The difference in the energies of these two is the energy which was being released on completion of reaction.

Andrews [41]4 years ago
3 0

a) Endothermic means that the tube will be cold.

b) Candle - exothermic

Lighting a gas stove - exothermic

Using an instant cold pack - endothermic.

Running a car's engine - exothermic.

c) Reactants have higher energy than the products, so it's exothermic cause the difference between energies converted to heat.

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Answer:

Probability of tunneling is 10^{- 1.17\times 10^{32}}

Solution:

As per the question:

Velocity of the tennis ball, v = 120 mph = 54 m/s

Mass of the tennis ball, m = 100 g = 0.1 kg

Thickness of the tennis ball, t = 2.0 mm = 2.0\times 10^{- 3}\ m

Max velocity of the tennis ball, v_{m} = 200\ mph = 89 m/s

Now,

The maximum kinetic energy of the tennis ball is given by:

KE = \frac{1}{2}mv_{m}^{2} = \frac{1}{2}\times 0.1\times 89^{2} = 396.05\ J

Kinetic energy of the tennis ball, KE' = \frac{1}{2}mv^{2} = 0.5\times 0.1\times 54^{2} = 154.8\ m/s

Now, the distance the ball can penetrate to is given by:

\eta = \frac{\bar{h}}{\sqrt{2m(KE - KE')}}

\bar{h} = \frac{h}{2\pi} = \frac{6.626\times 10^{- 34}}{2\pi} = 1.0545\times 10^{- 34}\ Js

Thus

\eta = \frac{1.0545\times 10^{- 34}}{\sqrt{2\times 0.1(396.05 - 154.8)}}

\eta = \frac{1.0545\times 10^{- 34}}{\sqrt{2\times 0.1(396.05 - 154.8)}}

\eta = 1.52\times 10^{-35}\ m

Now,

We can calculate the tunneling probability as:

P(t) = e^{\frac{- 2t}{\eta}}

P(t) = e^{\frac{- 2\times 2.0\times 10^{- 3}}{1.52\times 10^{-35}}} = e^{-2.63\times 10^{32}}

P(t) = e^{-2.63\times 10^{32}}

Taking log on both the sides:

logP(t) = -2.63\times 10^{32} loge

P(t) = 10^{- 1.17\times 10^{32}}

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Answer: 2. Solution A attains a higher temperature.

Explanation: Specific heat simply means, that amount of heat which is when supplied to a unit mass of a substance will raise its temperature by 1°C.

In the given situation we have equal masses of two solutions A & B, out of which A has lower specific heat which means that a unit mass of solution A requires lesser energy to raise its temperature by 1°C than the solution B.

Since, the masses of both the solutions are same and equal heat is supplied to both, the proportional condition will follow.

<em>We have a formula for such condition,</em>

Q=m.c.\Delta T.....................................(1)

where:

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<u>Proving mathematically:</u>

<em>According to the given conditions</em>

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  • equal heat is supplied to both the solutions, i.e. Q_A=Q_B
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