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3 years ago

How many grams of KCl are needed to prepare 1.00 L of a 2.00 M solution

1 answer:

8 0

Use the concentration and molar mass.

1.00 L (2.00 mol KCl/1 L)(74.6 g/ 1 mol KCl)= 149.2 grams

So, you need about 149 grams of KCl dissolved in 1 liter of water to prepare a 2.00 M solution.

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Which material is an insulator against electric current?

NemiM [27]

Answer:

b) a rubber tire

Explanation:

3 0

2 years ago

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What is the balanced form of the following equation? Br 2 + S 2 O 3 2– + H 2 O → Br 1– + SO 4 2– + H +

nikitadnepr [17]

Answer:

4Br₂+ 5H₂O+ S₂O₃²⁻ → 2SO₄²⁻ + 10H⁺ + 8Br⁻

Explanation:

Br₂ + S₂O₃²⁻ + H₂O → Br⁻ + SO₄²⁻ + H⁺

This is a redox reaction:

Br₂ changes the oxidation state from 0 to -1, so it was reduced

In the S₂O₃⁻² anion S changes the oxidation state from +2 to +6 in sulfate anion. (S₂O₃⁻², it is called thiosulfate)

We have protons in the main equation, so we assume we are in acidic medium:

Br₂ + 2e⁻ → 2Br⁻ Reduction

We balanced the bromide with 2, so the bromine has gained 2 electrons.

5H₂O + S₂O₃²⁻ → 2SO₄²⁻ + 10H⁺ + 8e- Oxidation

First of all, we add 2 to the sulfate anion in the product side, in order to balance the S.

As we have 8 O in right side, and 3 O in left side, we must add 5 O. We add 5 water in the place where the O are lower (reactant side).

Now, we have 10 H, in the reactant side, so we balance the product side with protons (10 H⁺).

Sulfur changed the oxidation state from +2 to +6, so it released 4 electrons, but, if you see thiosulfate anion you have 2 sulfurs so finally it has released 8 electrons.

Electrons are unbalanced so we multiply reduction x4, and oxidation x1.

(Br₂ + 2e⁻ → 2Br⁻) . 4 = 4Br₂ + 8e⁻ → 8Br⁻

(5H₂O + S₂O₃²⁻ → 2SO₄²⁻ + 10H⁺ + 8e-) . 1 = STAYS THE SAME.

We sum both half reactions, to cancel the elecetrons:

4Br₂ + 8e⁻ + 5H₂O + S₂O₃²⁻ → 2SO₄²⁻ + 10H⁺ + 8e- + 8Br⁻

Finally the balanced reaction is: 4Br₂+ 5H₂O+ S₂O₃²⁻ → 2SO₄²⁻ + 10H⁺ + 8Br⁻

5 0

3 years ago

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

2 years ago

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How many moles of lithium nitrate (LINO3) are in 256 mL of a 0.855 M solution?

sweet [91]

Answer:

There are 0.219 mol of LINO3

7 0

3 years ago

If you need to extract a 50 ml aqueous solution with 50 ml of dichloromethane, what is the minimum size of a separatory funnel y

tatuchka [14]

The dichloromethane (DCM) has less density than water and also the polarity of water is much more than DCM. So the mixture of water and dichloromethane will always be a heterogeneous mixture. In the mixture dichloromethane will be always up of the water layer. The volume of the separatory funnel which contains the mixture of DCM and water must have to be more than the total volume of the liquids thus the volume of the funnel will be more than (50+50) = 100mL.

The caution have to consider during the separation are-

1. The separatory funnel have to shake well with lid and have to settle down for some times until the two liquid separated.

2. The lid should be open very slowly as the vapor pressure of DCM is more and it will float on the water.

3. After this the stopcock should be opened and slowly the water will come out first followed by DCM.

7 0

2 years ago