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3 years ago

How long, in seconds, would it take for the concentration of A to decrease from 0.860 M to 0.310 M?

Chemistry

1 answer:

kogti [31]3 years ago

6 0

Answer:

2.038 seconds.

Explanation:

So, in the question above we are given the following parameters in order to solve this question. We are given a rate constant of 0.500 s^-, initial concentration= 0.860 M and final concentration= 0.310 M,the time,t =??.

Assuming that the equation for the first order of reaction is given below,that is;

A ---------------------------------> products.

Recall the formula below;

B= B° e^-kt.

Therefore, e^-kt = B/B°.

-kt = ln B/B°.

kt= ln B°/B.

Where B° and B are the amount of the initial concentration and the amount of the concentration remaining, k is the rate constant and t = time taken for the concentration to decrease.

So, we have; time taken,t = ln( 0.860/.310)/0.500.

==> ln 2.77/0.500.

==> time taken,t =2.038 seconds.

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3 years ago

How many grams of water will be produced from 50 g hydrogen reacting with 50 g oxygen?

DanielleElmas [232]

We need to first come up with a balanced equation:

$4H+O_{2}$ → $2H_{2}O$

We know that the molar ratio of hydrogen to oxygen to water now is 4:1:2.

Converting the amount of grams given to moles is as follows:

Hydrogen: $\frac{1mole}{1.008g}*50g=49.6mol$

Oxygen: $\frac{1mole}{15.999g}*50g=3.125mol$

We know now that the limiting reactant is oxygen. We can then know that the number of moles of water are produced are double the number of moles of oxygen used due to the ratio that we established at the beginning - 4:1:2.

So we now can use 6.25 moles of water as the amount produced.

Then we convert moles of water to grams:

$\frac{18.015g}{1mole} *6.25mol=112.59g$

Now we know that there are 112.59g of water produced when we start with 50g of hydrogen and 50g of water.

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3 years ago

True or false 12,785.000 has five significant digits.

Yuki888 [10]

Answer:

True

Explanation:

Significant digits include non-zero digits (unless the zero is between two non-zero numbers)

In 12,785.000, there are 5 non-zero digits:

1 2 7 8 5

4 0

3 years ago

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What determines density?

LUCKY_DIMON [66]

Answer:

D = m/v.

Explanation:

The density of a substance is the relationship between the mass of the substance and how much space it takes up (volume). The mass of atoms, their size, and how they are arranged determine the density of a substance. Density equals the mass of the substance divided by its volume;

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3 years ago

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Why is a homogeneous mixture not considered a pure substance? Question 6 options: A pure substance can be separated by physical

krok68 [10]

1. Why is a homogeneous mixture not considered a pure substance?

Answer:

A pure substance can be separated by chemical means, while a mixture can be separated by physical means.

2. What is true if mass is conserved in a reaction?

Answer:

There are equal numbers of atoms on both sides.

3. Methane reacts with oxygen then what are the products?

Answer:

carbon dioxide and water

4. Which one of the following is not a homogeneous mixture?

Answer:

vegetable soup

5. The substance is not uniform in appearance and each part of the mixture contains a combination of different ingredients in different ratios.

Answer:

heterogeneous mixtures

6. If a solution is saturated, which of these is true?

Answer:

More solvent can be dissolved

7. Which of these substances are molecules?

Answer:

All compounds are molecules but not all molecules are compounds. Molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. So correct option is 3 and 4.

8. What makes a solution a homogeneous mixture?

Answer:

It is uniform in composition.

9. When a solute is added to a solution, why does it remain homogeneous?

Answer:

The solute dissolves.

10. The chemical formula of glucose is C6H12O6, so it is classified as a(n)

Answer:

pure substance.

11. How many chlorine (Cl) atoms would be in 4 molecules of salt (4 NaCl)?

Answer:

12. In a solution of salt and water, which component is the solute?

Answer:

Salt

13. These substances are all H2O2, Li , NaCl , O2

Answer:

Pure Substances

14. If you have 5 grams of product after a chemical reaction, how many grams of reactants did you have at the start of the reaction?

Answer:

15. What is the difference between a compound and a mixture?

Answer:

A compound is a pure substance, but a mixture is not.

16. A firework exploding would be an example of a(n) ________.

Answer:

Exothermic reaction

17. If Lavoisier heated 100 grams of powdered mercuric oxide to produce 93 grams of liquid mercury, how much oxygen would be released?

Solution

2HgO ==> 2Hg + O2

Mass of HgO = 100 g

Molar mass of HgO = 216.59 g/mol

Moles = mass/molar mass = 0.46 moles

From balance chemcial equation

HgO : O2

2 = 1

0.46 = (1 × 0.46 ) ÷ 2 = 0.23 moles

mass of O2 = moles× molar mass = 0.23 × 32 = 7.36 g

18. Using the Law of Conservation of Matter, determine the number of grams of iron sulfide (FeS) that will be produced in this reaction.

Solution

12g Fe + 64g S → _____ g FeS

According to Law of Conservation of Matter, The total mass of reactant is equal to total mass of product , so the number of grams of iron sulfide (FeS) that will be produced in this reaction as follow.

12 + 64 = 76 g of FeS

Hope this Help.

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3 years ago

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