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WITCHER [35]
4 years ago
10

A scientist is at the hospital visiting a friend's young daughter, who has been

Chemistry
1 answer:
slava [35]4 years ago
5 0

Answer:

D

Explanation:

The scientist identifies the need to make a drug to cure the respiratory illnesses.

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A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. How much calcium is contained in 40.0 g of c
Temka [501]

Answer:

20.53 g.

Explanation:

  • Knowing that every 15.0 g of pure calcium fluoride contains 7.70 g of calcium.

<u>Using cross multiplication:</u>

15.0 g of pure calcium fluoride contains → 7.70 g of calcium.

40.0 g of pure calcium fluoride contains → ??? g of calcium.

<em>∴ The mass of Ca in 40.0 g of calcium fluoride</em> = (7.70 g)(40.0 g)/(15.0 g) = <em>20.53 g.</em>

6 0
3 years ago
Experiment #1A melting point of an old sample of Naphthalene was completed and a melting range of 77-83 oC was observed and reco
White raven [17]

Answer:

%error = 0.32%

Explanation:

Let's answer both questions, by parts.

1. Percentage error:

In this case, I do not have the video, but I do have the reported melting point of naphtalene which is 80.26 °C.

The expression to calculate the percentage error is the following:

%Error = absolute error / actual percentage. (1)

And the absolute error is:

Abs error = actual value - experimental value  (2)

But the experimental value is a range, so we just have to get a average of that:

Exp value = 77 + 83 / 2 = 80 °C

Now the absolute error:

Abs error = 80.26 - 80 = 0.26 °C

Finally the %error:

%error = (0.26 / 80.26) * 100

<h2>%error = 0.32%</h2>

2. Meaning of melting point range and %error

The melting point range just means that the sample of naphtalene has impurities, and when a sample of any compound has impurities, melting point tends to be low. However, this decrease of temperature is a wider range. But usually a range of just 5° C means that compound has little traces of impurities but it can still be used for reactions.

The %error means that the impurities of the sample are really low, so the sample is practically pure with little traces of impurities.

3 0
3 years ago
about how many times as much volume does a gas occupy compared to the same substance as a liquid or solid under normal condition
7nadin3 [17]

Answer:

Gases don't have definite volume. Gas molecules occupy all available space.

Explanation:

Consider the example of water. Which is present in three state solid, liquid and gas. In the form of ice its volume is less as compared to the liquid and gas, because molecules are tightly packed. If we melt the same ice we observe the volume is increase because molecules are now apart from each other. The distance between the molecules of water increased. If the same amount of water is evaporated the molecule of water will occupy all available space , and the distance between the water molecules get increased and inter molecular forces becomes negligible.

Properties of gases:

Molecule of gases randomly move every where and occupy all available space.

Gases don't have definite volume and shape.

Their densities are very low as compared to the liquid and solids.

Gas molecules are at long distance from each other therefore by applying pressure gases can be compressed.

The very weak inter molecular forces are present between gas molecules.

Properties of Liquid:

Liquid have definite volume but don,t have definite shape.

Their densities are high as compared to the gases but low as compared to the solids.

In liquid, molecules are close to each other and have greater inter molecular forces as compared to the gas molecules.

Properties of solids:

Solids have definite volume and shape.

In solids molecules are tightly pack and very close to each other.

Their melting and boiling point are every high.

The densities of solids are also very high as compared to the liquid and gas.

There are very strong inter molecular forces are present between solid molecules.

6 0
3 years ago
Which is the most important value of a graph
aksik [14]
X and y axis. i think
4 0
3 years ago
What is the need for and purpose of government
andriy [413]
In general, there are four main purposes of government to establish laws, maintain order and provide security, protect citizens from external threats, and promote the general welfare by providing public services.
4 0
4 years ago
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