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3 years ago

1.) Which of the following is an example of using creativity while doing background research?

Chemistry

1 answer:

ioda3 years ago

5 0

1) Answer is: D. Writing a hypothesis.

The scientific method is a process for experimentation that is used to explore observations.

Steps of the scientific method:

1) ask a question about something that is observed.

2) do background research.

3) construct a hypothesis, an attempt to answer questions with an explanation that can be tested.

4) test of hypothesis.

5) analyze collected data and draw a conclusion.

2) Answer is: A. Carbon and oxygen are chemically bonded in it.

A compound (in this example carbon dioxide CO₂) is a pure substance because its molecule cannot be broken down into simpler particles by physical means.

A chemical compound is a chemical substance composed of many identical molecules composed of atoms held together by chemical bonds.

Carbon dioxide (CO₂) are inorganic compounds with covalent bonds between carbon and oxygen.

3) Answer is: B. Components that are mixed can be in different states of matter.

A single substance can be used to make a mixture if the substance is composed of more than one element is not correct, because mixture is composed of at least two substances. For example mixture of water and alcohol ethanol.

There is a definite recipe to make each mixture, so the composition of a mixture is set is not correct, because composition of mixture can vary.

Components that are mixed can be in different states of matter is correct, for example mixture of salt (solid) and water (liquid).

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Regarding the Lyman series of hydrogen, calculate the frequency of the n = 5 line.

zvonat [6]

The Lyman series can be expressed in the formula 1/λ=RH(1−1/n2) where RH=1.0968×107m−1=13.6eVhc

Where n is a natural number greater than or equal to 2 (i.e. n = 2,3,4,...). Therefore, the lines seen in the image above are the wavelengths corresponding to n=2 on the right, to n=∞on the left (there are infinitely many spectral lines, but they become very dense as they approach to n=∞ (Lyman limit), so only some of the first lines and the last one appear).
The wavelengths (nm) in the Lyman series are all ultraviolet
:2 3 4 5 6 7 8 9 10 11
Wavelength (nm) 121.6 102.6 97.3 95 93.8 93.1 92.6 92.3 92.1 91.9 91.18 (Lyman limit)
In your case for the n=5 line you have to replace "n" in the above formula for 5 and you should get a value of 95 x 10^-9 m for the wavelength. then you have to use the other equation that convert wavelength to frequency.

4 0

3 years ago

svet-max [94.6K]

Explanation:

(1) The nucleus is positive and the electron cloud is positive.

(2) The nucleus is positive and the electron cloud is negative.

(3) The nucleus is negative and the electron cloud is positive.

(4) The nucleus is negative and the electron cloud is negative

4 0

3 years ago

Liquid hexane

maks197457 [2]

Answer: The mass of $H_2O$ produced is 2.52 g

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

For hexane:

Given mass of hexane = 1.72 g

Molar mass of hexane = 86.18 g/mol

Putting values in equation 1, we get:

$\text{Moles of hexane}=\frac{1.72g}{86.18g/mol}=0.020mol$

For oxygen gas:

Given mass of oxygen gas = 8.0 g

Molar mass of oxygen gas= 32 g/mol

Putting values in equation 1, we get:

$\text{Moles of water}=\frac{8.0g}{32g/mol}=0.25mol$

The chemical equation for the combustion of hexane follows:

$2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O$

By stoichiometry of the reaction:

If 2 moles of hexane reacts with 19 moles of oxygen gas

So, 0.020 moles of hexane will react with = $\frac{19}{2}\times 0.020=0.19mol$ of oxygen gas

As the given amount of oxygen gas is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.

Thus, hexane is considered a limiting reagent because it limits the formation of the product.

By the stoichiometry of the reaction:

If 2 moles of hexane produces 14 moles of $H_2O$

So, 0.020 moles of hexane will produce = $\frac{14}{2}\times 0.020=0.14mol$ of $H_2O$

We know, molar mass of $H_2O$ = 18 g/mol

Putting values in above equation, we get:

$\text{Mass of }H_2O=(0.14mol\times 18g/mol)=2.52g$

Hence, the mass of $H_2O$ produced is 2.52 g

4 0

3 years ago

How does the presence of a catalyst affect the enthalpy of a reaction? Group of answer choices 1. It depends on whether you are

Otrada [13]

Answer:

Option 3. The catalyst does not affect the enthalpy change ( $\Delta H_\text{rxn}$ ) of a reaction.

Explanation:

As its name suggests, the enthalpy change of a reaction ( $\Delta H_\text{rxn}$ ) is the difference between the enthalpy of the products and the reactants.

On the other hand, a catalyst speeds up a reaction because it provides an alternative reaction pathway from the reactants to the products.

In effect, a catalyst reduces the activation energy of the reaction in both directions. The reactants and products of the reaction won't change. As a result, the difference in their enthalpies won't change, either. That's the same as saying that the enthalpy change $\Delta H_\text{rxn}$ of the reaction would stay the same.

Refer to an energy profile diagram. Enthalpy change of the reaction $\Delta H_\text{rxn}$ measures the difference between the two horizontal sections. Indeed, the catalyst lowered the height of the peak. However, that did not change the height of each horizontal section or the difference between them. Hence, the enthalpy change of the reaction stayed the same.

6 0

3 years ago

Help please and thank you!

umka2103 [35]

D all are 1 because the left side equals the right

5 0

3 years ago

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