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3 years ago

Choose the correct statements from the list below:

Chemistry

1 answer:

ioda3 years ago

6 0

In chemistry:
When something is oxidized, it loses electrons.
When something is reduced, it gains electrons.
So the correct statements would be the second to last and third to last statements

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1. A 99.8 mL sample of a solution that is 12.0% KI by mass (d: 1.093 g/mL) is added to 96.7 mL of another solution that is 14.0%

Tatiana [17]

Answer:

The mass of PbI2 will be 18.2 grams

Explanation:

Step 1: Data given

Volume solution = 99.8 mL = 0.0998 L

mass % KI = 12.0 %

Density = 1.093 g/mL

Volume of the other solution = 96.7 mL = 0.967 L

mass % of Pb(NO3)2 = 14.0 %

Density = 1.134 g/mL

Step 2: The balanced equation

Pb(NO3)2(aq) + 2 KI(aq) ⇆ PbI2(s) + 2 KNO3(aq)

Step 3: Calculate mass

Mass = density * volume

Mass KI solution = 1.093 g/mL * 99.8 mL

Mass KI solution = 109.08 grams

Mass KI solution = 109.08 grams *0.12 = 13.09 grams

Mass of Pb(NO3)2 solution = 1.134 g/mL * 96.7 mL

Mass of Pb(NO3)2 solution = 109.66 grams

Mass of Pb(NO3)2 solution = 109.66 grams * 0.14 = 15.35 grams

Step 4: Calculate moles

Moles = mass / molar mass

Moles KI = 13.09 grams / 166.0 g/mol

Moles KI = 0.0789 moles

Moles Pb(NO3)2 = 15.35 grams / 331.2 g/mol

Moles Pb(NO3)2 = 0.0463 moles

Step 5: Calculate the limiting reactant

For 1 mol Pb(NO3)2 we need 2 moles KI to produce 1 mol PbI2 and 2 moles KNO3

Ki is the limiting reactant. It will completely be consumed ( 0.0789 moles). Pb(NO3)2 is in excess. There will react 0.0789/2 = 0.03945 moles. There will remain 0.0463 - 0.03945 = 0.00685 moles

Step 6: Calculate moles PbI2

For 1 mol Pb(NO3)2 we need 2 moles KI to produce 1 mol PbI2 and 2 moles KNO3

For 0.0789 moles KI we'll have 0.0789/2 = 0.03945 moles PbI2

Step 7: Calculate mass of PbI2

Mass PbI2 = moles PbI2 * molar mass PbI2

Mass PbI2 = 0.03945 moles * 461.01 g/mol

Mass PbI2 = 18.2 grams

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3 years ago

What is the purpose of a salt bridge?

k0ka [10]

Answer:

A salt bridge refers to a device used to form an electrochemical cell by providing a means to support the free flow of ions between the oxidation and reduction half-cell components. A salt bridge facilitates corrosion because corrosive reactions typically occur in the presence of electrochemical cells.

Explanation:

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2 years ago

What are acid-base reactions? precipitation reactions?

Ivenika [448]

Acid base reactions also known as neutralization reactions are reactions that occur between acids and bases thus the name. Anytime this happens the product will niether an acid or base it will be neutralized to a neutral pH as in that of pure water pH 7.
Precipitation reactions occur when cations and anions in aqueous solution combine to form an insoluble ionic solid called a precipitate. Whether or not such a reaction occurs can be determined by using the solubility rules for common ionic solids.

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3 years ago

A phospholipid has a glycerol attached to a phosphate group and two fatty acid chains. The head is hydrophilic, and the tail is

Rzqust [24]

Answer:

Because they are normally dissolved in water

Explanation:

The phospholipids can act as molecules that are carry inside or outside the cells, to transport it they are dissolved in another hydrophilic media, in this way the hydrophilic part can be in the outside part of the group of moleucles stick together like in cell membranes that are conformed by a double lipidic layer, in which the hydrophobic part it in the inside part. The cells normally are surrounded by different water solutions as the blood or another solutions.

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What is the scientific name for button mushrooms?

Maksim231197 [3]

It is Agaricus bisporus

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