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4 years ago

Anything in red is the question

Chemistry

1 answer:

laila [671]4 years ago

4 0

Answer:

Question 19: the three are molecular compounds.

Question 20: CuSO₄.5H₂O

Explanation:

<em>Question 19.</em>

C₂H₄

H₂O₂

All of them are the combination of two kinds of different atoms in fixed proportions.

C₂H₄: two carbon atoms per four hydrogen atoms

HF: one hydrogen atom per one fluorine atom

H₂O₂: two hydrogen atoms per two oxygent atoms

Thus, they all meet the definition of compund: a pure substance formed by two or more different elements with a definite composition.

Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.

Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.

<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.

Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol

Water is H₂O. Its molar mass is 18.015g/mol

Calling x the number of water molecules in the hydrate, the percentage of water is:

$\dfrac{18.015x}{18.015x+159.609}=36\%\\ \\ \\ \dfrac{18.015x}{18.015x+159.609}=0.36$

From which we can solve for x:

$18.015x=6.4854x+57.45924\\ \\ 11.5296x=57.45924\\ \\ x\approx4.98\approx5$

Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:

CuSO₄.5H₂O

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In 1911, Ernest Rutherford tested the atomic model existing at the time by shooting a beam of alpha particles (42He, helium nucl

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Answer:

At the time of Rutherford's experiment, the accepted model for the atom was the Thomson plum-pudding model of the atom, in which the atom consists of a "sphere" of positive charge distributed all over the sphere, with tiny negative particles (the electrons) inside this sphere.

In his experiment, Rutherford shot alpha particles towards a very thin sheet of gold foil. He observed the following things:

1- Most of the alpha particles went undeflected, but

2- Some of them were scattered at very large angles

3- A few of them were even reflected back to their original directions

Observations 2) and 3) were incompatible with Thomson model of the atom: in fact, if this model was true, all the alpha particle should have gone undeflected, or scattered at very small angles. Instead, due to observations 2) and 3), it was clear that:

- The positive charge of the atom was all concentred in a tiny nucleus

- Most of the mass of the atom was also concentrated in the nucleus

So, Rutherford experiment lead to a change in the atomic model of the atom, as it was clear that the plum-pudding model was no longer adequate to describe the results of Rutherford's experiment.

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3 years ago

Which statement about electrons is not true?a. One electron state is a bonding orbital between nucleib. One electron state is an

NemiM [27]

Answer:

b. One electron state is an anti-bonding orbital, which results in an absence of electron density between atoms.

Explanation:

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4 years ago

A gas has a volume of 25 ml, at a pressure of 1 atmosphere (1 atm). Increase the volume to 125 ml and the temperature remains co

vekshin1

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

$P_1V_1 = P_2V_2 \\$

Since we're finding the new pressure

$P_2 = \frac{P_1V_1}{V_2} \\$

We have

$P_2 = \frac{25 \times 1}{125} = \frac{25}{125} = \frac{1}{5} = 0.2 \\$

We have the final answer as

Hope this helps you

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3 years ago

A block of aluminium occupies a volume of 11.1 mL and weighs 43 g. What is it's density? Give answer with one decimal.

horrorfan [7]

Answer:

<h2>Density = 3.9 g/ mL</h2>

Explanation:

The density of a substance can be found by using the formula

$Density = \frac{mass}{volume}$

From the question

mass = 43 g

volume = 11.1 mL

Substitute the values into the above formula and solve for the density

That's

$Density = \frac{43}{11.1} \\ = 3.873873...$

We have the final answer as

Density = 3.9 g/ mL to one decimal place

Hope this helps you

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4 years ago

Electrons

blondinia [14]

1840 times lesser than

Explanation:

Robert A. Milikan from his experiment found that electrons carry exactly one unit of negative charge and that its mass is 1840 times lesser than the mass of a common hydrogen atom.

Robert Milikan performed the oil drop experiment and was able to determine the charge on an electron.
From Milikan's experiment, the relative mass of an electron was discovered to be about 1840 times lesser than the mass of a hydrogen atom.
A normal hydrogen atom is a proton with an actual mass of 1.67 x 10⁻²⁷kg.
Electrons weight 9.11 x 10⁻³¹kg which is 1840 less than the weight of a proton.

Learn more:

electrons brainly.com/question/10887448

#learnwithBrainly

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3 years ago