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Ivahew [28]
3 years ago
15

PLEASE HELP ME I HAVE NO IDEA “Heat (thermal) energy is being applied to the substance whenever the Bunsen Burner is on. Before

the solid begins to melt, how is this energy being used?”
Chemistry
1 answer:
svetlana [45]3 years ago
5 0

TLDR: The energy was being used simply to heat the substance up.

Whenever something melts, it performs what is called a "phase transition", where the state of matter moves from one thing to something else. You can see this in your iced drink at lunch; as the ice in the cup of liquid heats up, it reaches a point where it will eventually "change phase", or melt. The same can be achieved if you heat up that water enough, like if you're cooking; when you boil eggs, the water has so much thermal energy it can "change phase" and become a gas!

However, water doesn't randomly become a boiling gas, it has to heat up for a while before it reaches that temperature. For a real-life example, the next time you cook something, hold you hand above the water before it starts boiling. You'll see that that water has quite a high temperature despite not boiling.

There's a lot of more complex chemistry to describe this phenomena, such as the relationship between the temperature, pressure, and what is called the "vapor pressure" of a liquid when describing phase changes, but for now just focus on the heating effect. When ice melts, it doesn't seem like its heating up, but it is. The ice absorbs energy from its surroundings (the warmer water), thus heating up the ice and cooling down the water. Similarly, the bunsen burner serves to heat up things in the lab, so before the solid melts in this case it was simply heating up the solid to the point that it <u>could</u> melt.

Hope this helps!

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During our phase changes lab, where did we place the thermometer?
IrinaK [193]

The thermometer must be <u>in contact with the ice/water only</u>

Explanation:

In this experiment in the lab, the aim is to measure the specific latent heat of fusion of water.

The specific latent heat of fusion of a substance is the amount of heat energy required to completely melt a certain amount of the substance, mathematically:

\lambda = \frac{Q}{m}

where

Q is the heat supplied to the substance

m is the mass of the substance

In this experiment, the aim is to measure the specific latent heat of fusion of water. In order to do that, a mix of ice/water is heated with a certain amount of heat Q, and then it is evaluated the amount of mass m that undergoes melting.

An important precaution that must be taken in this experiment is that the temperature of the water/ice mixture remains constant and equal to the melting point of ice (otherwise, part of the heat supplied to the mixture is used to increase the temperature of the water, resulting in an inaccurate measure of Q). Therefore, a thermometer must be used to check constantly the temperature, and this thermometer must be placed inside the ice/water mixture only (It should not touch the saucepan, whose temperature can be higher).

So, the correct answer is

in contact with the ice/water only

Learn more about specific heat:

brainly.com/question/3032746

brainly.com/question/4759369

#LearnwithBrainly

3 0
3 years ago
Most of our DNA consists of regions that do not code for any proteins True or False
Lady bird [3.3K]
The Answer you are looking for is true
5 0
3 years ago
Why do you think the location surrounding the pacific ocean is known as the ring of fire
snow_tiger [21]
It is on a plate boundary so there are a lot of volcanoes in that area. All the volcanoes form a "ring" around the plate boundary.
6 0
3 years ago
In a certain city, electricity costs $0.15 per kW·h. What is the annual cost for electricity to power a lamp-post for 6.00 hours
Vanyuwa [196]

(a) Power of bulb is 100 W, converting this into kW.

1 W=\frac{1}{1000}kW

Thus,

100 W =\frac{100}{1000}kW=0.1 kW

The bulb is used for 6 hours per day for a year, in 1 year there are 365 days thus, total hours will be:

t=6\times 365=2190 h

Electricity used will depend on power and number of hours as follows:

E=P\times t=0.1 kW\times 2190 h=219 kW.h

The cost of electricity is $0.15 per kW.h thus, cost of electricity for 219 kW.h will be:

Cost=\$ (219\times 0.15)=\$ 32.85

Therefore, annual cost of incandescent light bulb is \$ 32.85

(b) Power of bulb is 25 W, converting this into kW.

1 W=\frac{1}{1000}kW

Thus,

100 W =\frac{25}{1000}kW=0.025 kW

The bulb is used for 6 hours per day for a year, in 1 year there are 365 days thus, total hours will be:

t=6\times 365=2190 h

Electricity used will depend on power and number of hours as follows:

E=P\times t=0.025 kW\times 2190 h=54.75 kW.h

The cost of electricity is $0.15 per kW.h thus, cost of electricity for 54.75 kW.h will be:

Cost=\$ (54.75\times 0.15)=\$ 8.21

Therefore, annual cost of fluorescent bulb is \$ 8.21.

7 0
3 years ago
A sample of gas is observed to effuse through a pourous barrier in 4.98 minutes. Under the same conditions, the same number of m
kogti [31]

Answer:

The molar mass of the unknown gas is \mathbf{ 51.865 \  g/mol}

Explanation:

Let assume that  the gas is  O2 gas

O2 gas is to effuse through a porous barrier in time t₁ = 4.98 minutes.

Under the same conditions;

the same number of moles of an unknown gas requires  time t₂  =  6.34 minutes to effuse through the same barrier.

From Graham's Law of Diffusion;

Graham's Law of Diffusion states that, at a constant temperature and pressure; the rate of diffusion of a gas is inversely proportional to the square root of its density.

i.e

R \  \alpha  \ \dfrac{1}{\sqrt{d}}

R = \dfrac{k}{d}  where K = constant

If we compare the rate o diffusion of two gases;

\dfrac{R_1}{R_2}= {\sqrt{\dfrac{d_2}{d_1}}

Since the density of a gas d is proportional to its relative molecular mass M. Then;

\dfrac{R_1}{R_2}= {\sqrt{\dfrac{M_2}{M_1}}

Rate is the reciprocal of time ; i.e

R = \dfrac{1}{t}

Thus; replacing the value of R into the above previous equation;we have:

\dfrac{R_1}{R_2}={\dfrac{t_2}{t_1}}

We can equally say:

{\dfrac{t_2}{t_1}}=  {\sqrt{\dfrac{M_2}{M_1}}

{\dfrac{6.34}{4.98}}=  {\sqrt{\dfrac{M_2}{32}}

M_2 = 32 \times ( \dfrac{6.34}{4.98})^2

M_2 = 32 \times ( 1.273092369)^2

M_2 = 32 \times 1.62076418

\mathbf{M_2 = 51.865 \  g/mol}

7 0
3 years ago
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