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3 years ago

Can someone tell me how to identify the number of significant figures?

Chemistry

1 answer:

igor_vitrenko [27]3 years ago

8 0

Answer:

Non-zero digits are always significant.

Any zeros between two significant digits are significant.

A final zero or trailing zeros in the decimal portion ONLY are significant. If a number ends in zeros to the right of the decimal point, those zeros are significant.

Explanation:

1.138 has 4 significant figures, which are 1, 1, 3 and 8. The numbers after the decimal point are decimals and are significant figures.

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What does the pH of a solution have to be in order to be a base?

VMariaS [17]

Explanation:

pH is used to measure the concentration of H+ ions ([H+]) and therefore, whether a substance is acidic or basic (alkaline). Solutions with a pH of less than seven are acidic, while those with a pH greater than seven are basic (alkaline).

8 0

4 years ago

Read 2 more answers

Is O2 always a double bond?

Dima020 [189]

O-O single bonds and H-O single bonds in $\text{H}_2\text{O}_2$ molecules.
H-O single bonds in $\text{H}_2\text{O}$ molecules.
O=O double bonds in $\text{O}_2$ molecules.

<h3>Explanation</h3>

How many valence electrons do atoms in each molecule need for them to be stable?

Each H atom needs two valence electrons to be stable.
Each atom of an element other than H needs eight valence electron to be stable.

There are two H atoms and two O atoms in an $\text{H}_2\text{O}_2$ molecule. Atoms in each $\text{H}_2\text{O}_2$ need $2 \times 1 + 2\times 2 = 6$ more electrons to be stable.
There are two H atoms and one O atom in an $\text{H}_2\text{O}$ molecule. Atoms in each $\text{H}_2\text{O}$ molecule need $2 \times 1 + 2= 4$ more electrons to be stable.
There are two O atoms in an $\text{O}_2$ molecule. Atoms in each $\text{O}_2$ molecule need $2 \times 2 = 4$ more electrons to be stable.

How many chemical bonds in each molecule?

Each chemical bond adds one valence electron to each bonding atom. Each chemical bond connects two atoms. As a result, each chemical bond adds two valence electrons to the molecule.

Each $\text{H}_2\text{O}_2$ molecule needs $6 / 2 = 3$ chemical bonds.
Each $\text{H}_2\text{O}$ molecule needs $4 / 2 = 2$ chemical bonds.
Each $\text{O}_2$ molecule needs $4 /2= 2$ chemical bonds.

What chemical bonds are these? Again, each H atom needs only one more valence electron to be stable. It will share only one electron with O and form one H-O bond. The rest of the chemical bonds are between O atoms.

There are two H atoms in each $\text{H}_2\text{O}_2$ molecule, which form two H-O bonds. Two of the three chemical bonds in this molecule are H-O. The other is an O-O single bond between the two O atoms.
There are two H atoms in each $\text{H}_2\text{O}$ molecule, which form two H-O bonds. Both chemical bonds in this molecule are H-O. There's no O-O bond in this molecule.
There is no H atom in $\text{O}_2$ molecules. Both chemical bonds are between O atoms. However, there are only two O atoms. There must be two chemical bonds between the two O atoms. That bond will be an O-O double bond.

3 0

3 years ago

Read 2 more answers

One of the waste byproducts of a nuclear reactor using uranium-235 is strontium-90 with half-life of about 28 years. If we have

e-lub [12.9K]

Answer:

(a) 140 years

(b) 3.125 pounds

Explanation:

<u>QuestIons</u>

(a) How long is five half-life

(b) How much radioactive strontium is left after five half-life

Given that:

Half-life is about 28 years; &

There are 100 pounds of this radioactive waste

Five half-life will be;

= 28 × 5

= 140 years

The amount of radioactive remaining after five half-life is:

$= 100 \times( \dfrac{1}{2}) ^5$

= 100 × 0.03125

= 3.125 pounds

5 0

3 years ago

Given the reaction agi(s) ↔ ag+(aq) + i-(aq) solution equilibrium is reached in the system when

Julli [10]

Missing question:
1) the rate of dissolving reaches zero
<span>2) the rate of crystallization reaches zero </span>
3) the rate of dissolving is zero and the rate of crystallization is greater than zero.
<span>4) both the rate of dissolving and the rate of crystallization are equal and greater than zero.
</span>
Answer is: 4) both the rate of dissolving and the rate of crystallization are equal and greater than zero.
Silver chloride (AgCl) dissolves and form silver and chlorine ions, in the same time silver and chlorine ions crystallizate and form solid salt silver chloride.
In equilibrium rates of dissolvinf and crysallization and concentration of ions do not change.

7 0

3 years ago

You make two dilutions. You take 83.52 mL of the stock solution and dilute to 500.0 mL to make Solution #1. You then add 52.27 m

kati45 [8]

Answer:

The answer to the question is;

The concentration of the Solution #1 in terms of molarity is

0.16704X moles/litre.

Explanation:

Let the concentration of the stock solution be X moles/liter

Therefore, 83.52 ml of the stock solution contains

83.52×(X/1000) moles

Dilution of 83.52 ml of X to 500 ml gives solution 1 with a concentration of

500 ml of solution 1 contains 83.52×(X/1000) moles

Therefore 1000 ml or 1 litre contains 2×83.52×(X/1000) moles = 0.16704X moles/litre

The molarity of solution 1 is 0.16704X moles/litre.

8 0

4 years ago