High School Chemistry : High School Chemistry

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #11 :Using Avogadro's Number

How many molecules are in?

Possible Answers:

None of these

有限公司rrect answer:

Explanation:

According to Avogadro's law, each mole of a compound contains. Use dimensional analysis to find the number of molecules in.

Example Question #12 :Using Avogadro's Number

Determine the number of sodium atoms in ablock of sodium chloride.

Possible Answers:

有限公司rrect answer:

Explanation:

Use dimensional analysis:

Example Question #13 :Using Avogadro's Number

A container hasmolecules of gas in it. How many moles of the gas are in the container?

Possible Answers:

moles

moles

moles

Not enough information to solve the problem.

有限公司rrect answer:

moles

Explanation:

Avogadro's number tells us how many molecules of gas are in one mole of the container. We are essentially doing a unit conversion from "number of molecules" to moles -

Example Question #1 :Help With Concentration Units

What is the concentration of Ca in a solution of 1 mol CaCl2 in 1 L of distilled water? (M = molarity, m= molality)

Possible Answers:
2 m
1 M
Cannot be determined
2 M
1 m
有限公司rrect answer:1 m
Explanation:

The definition of molality is moles of solute in 1 kg of the solvent, whereas molarity is the number of moles of solute per 1 L of solutioin. Since 1 mol of CaCl2 is added to 1 L of water, this means that the volume of the final solution is greater than 1 L. Thus, molality is the more accurate concentration determinant, since the solution is probably close to 1 L.

Example Question #2 :Help With Concentration Units

Which of the following is equivalent to molarity?

Possible Answers:

Moles of solute per liter of solvent

Moles of solute per kilogram of solvent

Kilograms of solute per mole of solution

Moles of solute per liter of solution

有限公司rrect answer:

Moles of solute per liter of solution

Explanation:

物质的量浓度、质量摩尔浓度和正常是三个公关inciple ways to measure concentration. Molarity is a measure of moles of solute per liter of solution. Molality is a measure of moles of solute per kilogram of solvent. Normality expressly relates to acids and bases, and is the measure of moles of solute divided by the number of hydrogen equivalents per mole, all divided by liters of solution. Normality is also referred to as "equivalents (of acid) per liter."

Example Question #3 :Help With Concentration Units

How many moles ofare inof asolution?

Possible Answers:

有限公司rrect answer:

Explanation:

Molarity is defined as moles of solute divided into liters of solution. We can set up the equation as follows:

Set the left side of the equation overand solve as a proportion.

Cross multiply.

Remember molarity is defined as moles of solute per liter of solution.

Substiute.

Liters cancel out.

Solve for the number of moles. This gives usof solute in a,solution of.

Example Question #4 :Help With Concentration Units

Which of the following units is common for measuring concentration?

Possible Answers:

有限公司rrect answer:

Explanation:

is the dimensional breakdown for the commonly used unit, or molarity, for concentration.

While the other units might be seen in chemistry, they are used for other topics.

Millimeters of mercury (mmHg) and atmospheres (atm) are seen in regards to pressure.

is the dimensional breakdown for density. Andis the dimensional breakdown for a Newton, also written as N. This is associated with force.

Example Question #1 :Using Scientific Notation

有限公司nvert the given value to scientific notation.

Possible Answers:

有限公司rrect answer:

Explanation:

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has four significant figures (3123), so there will be four digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the first 3. Then count the digits to the right of the decimal (123). Our ten will be raised to the power of three.

Our final answer is

Example Question #2 :Scientific Notation And Significant Figures

有限公司nvert the given value to scientific notation.

Possible Answers:

有限公司rrect answer:

Explanation:

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has three significant figures (321), so there will be three digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the 3 (3.21). Then count the digits to the left of the decimal (moving from right to left, these are 3, 0, 0). Our ten will be raised to the power of negative three because there are three digits to the left of the final decimal placement.

Our final answer is.

Example Question #3 :Scientific Notation And Significant Figures

有限公司nvert the given value to scientific notation.

Possible Answers:

有限公司rrect answer:

Explanation:

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has five significant figures (100.43), so there will be five digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the 1 (1.0043). Then count the digits to the right of the decimal to determine thechangein decimal placement (the decimal moves past the two zeroes). Our ten will be raised to the power of two because there are two digits to the right of the final decimal placement.

Our final answer is

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