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3 years ago

Select all the correct answers.

Chemistry

1 answer:

kupik [55]3 years ago

4 0

The two ways the cathode ray tube experiment changed scientists'

understanding of the atom was it showing that atoms can be divided into

smaller parts and all atoms contain electrons.

J.J Thompson was the scientist which performed the cathode ray tube

experiment and was able to ascertain it was negatively charged as a result

of it being deflected to the positive electrode.

His observation showed that the atoms contain sub-atomic particles called

electrons which are negatively charged.

Read more on brainly.com/question/15361325

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A compound is 7.74% hydrogen and 92.26% carbon by mass. At 100°C a 0.6883 g sample of the gas occupies 250 mL when the pressure

ycow [4]

Answer: The molecular formula for the compound is $C_6H_6$

Explanation:

We are given:

Percentage of C = 92.26 %

Percentage of H = 7.74 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 92.26 g

Mass of H = 7.74 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{92.26g}{12g/mole}=7.68moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{7.74g}{1g/mole}=7.74moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.68 moles.

For Carbon = $\frac{7.68}{7.68}=1$

For Hydrogen = $\frac{7.74}{7.68}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H = 1 : 1

The empirical formula for the given compound is $CH$

Calculating the molar mass of the compound:

To calculate the molecular mass, we use the equation given by ideal gas equation:

PV = nRT

Or,

$PV=\frac{m}{M}RT$

where,

P = pressure of the gas = 820 torr

V = Volume of gas = 250 mL = 0.250 L (Conversion factor: 1 L = 1000 mL )

m = mass of gas = 0.6883 g

M = Molar mass of gas = ?

R = Gas constant = $62.3637\text{ L. torr }mol^{-1}K^{-1}$

T = temperature of the gas = $100^oC=(100+273)K=373K$

Putting values in above equation, we get:

$820torr\times 0.250L=\frac{0.6883g}{M}\times 62.3637\text{ L torr }mol^{-1}K^{-1}\times 373K\\\\M=\frac{0.6883\times 62.3637\times 373}{820\times 0.250}=78.10g/mol$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{Molecular mass}}{\text{Empirical mass}}$

We are given:

Mass of molecular formula = 78.10 g/mol

Mass of empirical formula = 13 g/mol

Putting values in above equation, we get:

$n=\frac{78.10g/mol}{13g/mol}=6$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 6)}H_{(1\times 6)}=C_6H_6$

Hence, the molecular formula for the compound is $C_6H_6$

8 0

3 years ago

How do you write a polynomial in standard form?

olchik [2.2K]

One way to write a polynomial is in standard form. In order to write any polynomial in standard form, you look at the degree of each term. You then write each term in order of degree, from highest to lowest, left to write. First, look at the degrees for each term in the expression. and in this way you will be able to write polynominal in standard form.

8 0

3 years ago

How do some deep-water bacteria in the ocean make food?

Umnica [9.8K]

Answer:

They make food by using chemosynthesis.

Explanation:

6 0

3 years ago

HELP PLEASE Explain why the elements of group 1 and 7 are quite reactive

Sauron [17]

Group 17 is the most readily reduced elements on the periodic table, meaning that they are so close to being a stable elements, only missing 1 electron to complete their valance electron shell. Thus they will essentially react with anything to get that last electron!

Group 1 elements are extremely reactive because they are the most readily oxidized, they are very close to reaching stability by giving up only 1 electron. Thus they will react with almost anything to give up their electron.

8 0

4 years ago

7. A sample of a compound that contains only chlorine and oxygen reacts with excess hydrogen to produce 0.233 grams of hydrochlo

Snowcat [4.5K]

Answer:

ClxOy + H2 > HCl + H2O

HCl = 0.233/37 = 0.006 mol H2O = 0.403/180.02 mol

HCl = 0.006/0.022 H2O = 0.022/0.006

= 1 = 4

Cl2O4 + 5H2 > 2HCl + 4H2O

I'm think that's the answer

5 0

3 years ago