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3 years ago

Please help me !!!!

Chemistry

1 answer:

just olya [345]3 years ago

3 0

Answer:

12, 28, 16

Explanation:

If we are trying to find mass, neutrons are our guy. 28 "mass points" means 28 neutrons. Each neutron is one point

We know there are 12 protons and electrons if we look at a table of elements, the number in the top-left is always the number of protons and we can subtract mass from the protons to get our electrons

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Balance the following skeleton reaction in acidic solution (if the coefficient is 1, put 1; if the coefficient is 0, put 0) and

Mashcka [7]

Answer:

2 CrO42- + 3N2O + 10 H+ -----> 2Cr3+ + 6NO + 5H2O

Explanation:

2 CrO42- + 3N2O + 10 H+ -----> 2Cr3+ + 6NO + 5H2O

Oxidizing agent: -----------------------------> CrO42-

Reducing agent: ----------------------------> N2O

explanation:

in CrO4-2 oxdiation state of Cr = +6

in Cr+3 oxidation state = +3

+6 oxidation state changed from +3 it is reduction .

so CrO4-2 is oxidizing agent

atomatically

N2O should be reducing agent

7 0

3 years ago

1. A gas having the following composition is burnt under a boiler with 50% excess air.

jeka94

The composition of the stack gas are :

$CH_4$ = 0.8713

$C_3H_8$ = 0.0202

CO = 0.107

<h3 /><h3>What is a mole fraction?</h3>

The ratio of the number of moles of one component of a solution or other mixture to the total number of moles representing all of the components.

Assuming 100 g of the stack gas. Calculate the mass of each species in this sample according to their percentages.

Mass of $CH_4$ : 70% of 100 g = 70 g

Mass of $C_3H_8$ : 15% of 100 g = 15 g

Mass of CO : 15% of 100 g = 15 g

Now calculate the number of moles of each species:

Number of moles of $CH_4$ : $\frac{70 g}{16.04 g/mol}$ = 4.3 mole

Number of moles of $C_3H_8$ : $\frac{15 g}{144.1 g/mol}$ = 0.10 mole

Mass of CO : $\frac{15 g}{28.01 g/mol}$ = 0.53 mole

Now to calculate the mole fraction of each we use the formula:

Mole fraction of $CH_4$ : $\frac{4.3}{4.935}$ = 0.8713

Mole fraction of $C_3H_8$ : $\frac{0.10}{4.935}$ = 0.0202

Mole fraction of CO : $\frac{0.53}{4.935}$ = 0.107

Hence, composition of the stack gas are:

$CH_4$ = 0.8713

$C_3H_8$ = 0.0202

CO = 0.107

Learn more about mole fraction here:

brainly.com/question/13135950

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8 0

2 years ago

During a titration the following data were collected. A 50.0 mL portion of an HCl solution was titrated with 0.500 M NaOH; 200.

Travka [436]

Answer: The mass of HCl present in 500 mL of acid solution is 36.5 grams

Explanation:

To calculate the concentration of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is HCl

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is NaOH.

We are given:

$n_1=1\\M_1=?M\\V_1=50.00mL\\n_2=1\\M_2=0.500M\\V_2=200.mL$

Putting values in above equation, we get:

$1\times M_1\times 50.00=1\times 0.500\times 200\\\\M_1=\frac{1\times 0.500\times 200}{1\times 50.00}=2M$

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

Molar mass of HCl = 36.5 g/mol

Molarity of solution = 2 M

Volume of solution = 500 mL

Putting values in above equation, we get:

$2mol/L=\frac{\text{Mass of solute}\times 1000}{36.5g/mol\times 500}\\\\\text{Mass of solute}=\frac{2\times 36.5\times 500}{1000}=36.5g$

Hence, the mass of HCl present in 500 mL of acid solution is 36.5 grams

4 0

3 years ago

You begin pouring sodium chloride into a glass of water. For a long time, the sodium chloride just dissolves in the water, but s

Gennadij [26K]

Answer:

Option D: The water is saturated

Explanation:

Solubility is the term used to designate the maximum amount of a solute that can be dissolved in a given amount of solvent, at a given temperature and pressure.

At start, you begin with pure water in the glass. This water is a pure substance, not a solution.

When you begin pouring sodium chloride into the glass of water, a solution, i.e. a homogenous mixture of solute and solvent, is formed.

This solution, at first, is diuted, which means that it contanins just few grams (matter) of the solute dissolved.

As, more sodium chloride is dissolved, the solution becomes more concentrated but is unsaturated. At some point, the water cannot dissolve more sodium chloride, because it has reached the maximum amount that can contain at that temperature and pressure. Then, the solution is saturated.

You can tell that the water is saturated, ie it contaiins the maximum amount of sodium chloride that can be dissolved, by that amount of water, at the given temperature, because from that point, you will note that as you pour more sodium chloride, it begins to pile up at the bottom of the glass. Hence, the true statement is the letter D: the water is saturated.

5 0

3 years ago

A compound that is composed of only carbon and hydrogen contains 85.7% c and 14.3% h by mass. what is the empirical formula of t

Anna35 [415]

The empirical formula is CH2

8 0

3 years ago