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4 years ago

A student collected the data shown in the table below during an experiment.

Chemistry

1 answer:

pentagon [3]4 years ago

3 0

Answer: The answer is C. A mercury thermometer is better to measure very small changes in temperature.

Explanation:

i took this quiz and this is the answer .

A) A mercury thermometer can measure the freezing point of a liquid that freezes at −80 °C.

B) An alcohol thermometer can measure the boiling point of a liquid that boils at 80 °C.

C) A mercury thermometer is better to measure very small changes in temperature.

D) An alcohol thermometer is better to measure the boiling points of colorless liquids.

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What is an example of kinetic energy? Question 7 options: A frisbee flying through the air A car in the garage A box sitting on

Amiraneli [1.4K]

Kinetic energy is energy that comes from motion. Anything that is currently in motion has kinetic energy.

Let’s look at each example to determine if they have kinetic energy.

First off, a car in the garage: let’s ask ourselves- Is the car in motion?
No, it is sitting in the garage. It is not moving; therefore it doesn’t have any kinetic energy.

Next, a box sitting on a shelf: let’s ask ourselves the same question- Is the box in motion?
No, it is sitting on the shelf. Again, it is not moving. It doesn’t have any kinetic energy.

Our third item is a ball lodged in a tree: again, we will ask ourselves the same question- Is the object moving?
No, it isn’t moving. Again, since it is not moving, it will not have kinetic energy.

Our last item is a frisbee flying through the air: asking ourselves the same question- Is it moving?
Yes, the object is moving. Yes, it has kinetic energy.

The frisbee flying through the air has kinetic energy.

4 0

3 years ago

Read 2 more answers

If you have a solution that contains 46.85 g of codeine, C18H21NO3, in 125.5 g of ethanol, C2H5OH, what is the mole fraction of

irakobra [83]

Answer:

0.22

Explanation:

Given, Mass of $C_{18}H_{21}NO_3$ = 46.85 g

Molar mass of $C_{18}H_{21}NO_3$ = 299.4 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{46.85\ g}{299.4\ g/mol}$

$Moles\ of\ C_{18}H_{21}NO_3= 0.1565\ mol$

Given, Mass of $C_{2}H_{5}OH$ = 125.5 g

Molar mass of $C_{2}H_{5}OH$ = 46.07 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{125.5\ g}{46.07\ g/mol}$

$Moles\ of\ C_{2}H_{5}OH= 0.5535\ mol$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ codeine=\frac {n_{codeine}}{n_{codeine}+n_{ethanol}}$

$Mole\ fraction\ of\ codeine=\frac{0.1565}{0.1565+0.5535}=0.22$

4 0

3 years ago

What is the half-life of an isotope that decays to 6.25% of its original activity in 18.9 hours?

inessss [21]

Radioactive material obeys 1st order decay kinetics,
For 1st order reaction, we have
k = $\frac{2.303}{t}Xlog \frac{\text{initial conc.}}{\text{final conc.}}$
where, k = rate constant of reaction

Given: Initial conc. 100, Final conc. = 6.25, t = 18.9 hours

∴ k = $\frac{2.303}{18.9} X log \frac{100}{6.25}$ = 0.1467 hours^(-1)

Now, for 1st order reactions: half life = $\frac{0.693}{k} = \frac{0.693}{0.1467}$ = 4.723 hours.

8 0

3 years ago

The standard enthalpy change for the following reaction is 873 kJ at 298 K.

Flura [38]

Answer: - 436.5 kJ.

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation.

The given chemical reaction is,

$2KCl(s)\rightarrow 2K(s)+Cl_2(g)$ $\Delta H_1=873kJ$

Now we have to determine the value of $\Delta H$ for the following reaction i.e,

$K(s)+\frac{1}{2}Cl_2(g)\rightarrow KCl(s)$ $\Delta H_2=?$

According to the Hess’s law, if we divide the reaction by half then the $\Delta H$ will also get halved and on reversing the reaction , the sign of enthlapy changes.

So, the value $\Delta H_2$ for the reaction will be: