Pipette Use and Solution Preparation

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Questions and Answers

What is the smallest volume that a P10 pipette can effectively measure?

1 ml

1000 μl

100 μl

10 μl (correct)

What is the principle of operation behind pipettes?

Electrolysis

Liquid displacement

Air displacement (correct)

Evaporation

What should be the maximum acceptable precision when using pipettes?

1% (correct)

10%

0.5%

When weighing volumes of distilled water, which piece of equipment is necessary?

Balance Signup and view all the answers

What is the main purpose of detachable and disposable tips on pipettes?

To reduce contamination Signup and view all the answers

Which of the following pipettes would be used to measure 1000 μl?

P1000 Signup and view all the answers

What is one common source of error when using pipettes?

Human error in measurement Signup and view all the answers

What is the relationship between milliliters and microliters?

1 ml = 1000 μl Signup and view all the answers

What is the primary liquid component of a solution known as?

Solvent Signup and view all the answers

If the solvent is water, how is the solution referred to?

Aqueous solution Signup and view all the answers

Which formula represents the concentration of a solution?

Solution concentration = amount of solute / amount of solution Signup and view all the answers

What can the amount of solute and solution be expressed in?

Mass or volume Signup and view all the answers

Why is knowledge of the preparation of aqueous solutions important?

Living organisms consist mainly of water. Signup and view all the answers

How is solution precision typically assessed?

Through averaging multiple readings Signup and view all the answers

What is the overall goal of part B: Sample Preparation?

To prepare solutions from solutes and solvents Signup and view all the answers

In a liquid solution, the component being dissolved is referred to as what?

Solute Signup and view all the answers

What is the % by mass concentration of a solution containing 10 g of NaCl in 200 g of solution?

2.5% (w/w) Signup and view all the answers

If 30 ml of ethanol is mixed with water to make a 150 ml solution, what is the % by volume concentration of ethanol?

25% (v/v) Signup and view all the answers

What is the % weight by volume concentration of a solution when 5 g of KCl is dissolved in 200 ml of water?

2.5% (w/v) Signup and view all the answers

What is the molarity of a solution if 0.5 moles of glucose are dissolved in 2 L of water?

0.5 M Signup and view all the answers

Which unit is used to express the % weight by volume of a solution?

g of solute / 100 ml of solution Signup and view all the answers

If a solution has a molarity of 1.5 M and contains 3 moles of NaOH, what is the volume of the solution in liters?

1 L Signup and view all the answers

Which of the following statements about % by volume (% v/v) concentration is true?

It is calculated using the volume of solute. Signup and view all the answers

What is the % by mass concentration of a solution if 4 g of solute is dissolved in 200 g of solution?

2% (w/w) Signup and view all the answers

How many grams of CuSO4 are needed for the preparation of 10ml of 5M solution given that the molecular weight is 159.61?

7.9805 g Signup and view all the answers

How is the concentration of a solution affected when it is diluted?

The concentration decreases Signup and view all the answers

Which of the following best describes a saturated solution?

It cannot hold more solute at a given temperature Signup and view all the answers

What is necessary to perform a dilution correctly?

Adding the solvent to the solute Signup and view all the answers

What is the percentage weight by volume concentration of a solution made by dissolving 5g of NaCl in 50ml of water?

10% Signup and view all the answers

How do you calculate the molarity of a solution when 11g of CaCl2 are dissolved in 100ml of water?

Convert grams to moles, then divide by liters Signup and view all the answers

If you prepare 100ml of a 0.1M NaOH solution using a 1M NaOH solution, how much of the 1M solution is used?

10ml Signup and view all the answers

To prepare 50ml of a 1X NaOH solution from a 10X solution, how much of the 10X solution should be used?

10ml Signup and view all the answers

What does the variable C1 represent in the dilution formula C1V1 = C2V2?

Initial Concentration Signup and view all the answers

If the final volume of a dilution is doubled while keeping the amount of solute constant, what happens to the concentration?

It halves Signup and view all the answers

Which of the following statements about dilutions is incorrect?

The amount of solvent can be ignored Signup and view all the answers

What must be true about the units in the dilution equation C1V1 = C2V2?

They must be homogeneous Signup and view all the answers

Which of the following illustrates the concept of molarity?

Moles of solute divided by liters of solution Signup and view all the answers

In the context of dilutions, what is the main purpose of adding solvent to a solution?

To decrease the concentration Signup and view all the answers

Study Notes

Pipette Use

Pipettes are laboratory tools for handling and dispensing small liquid volumes.
Measurements are typically in microliters (μL), which are 1/1000 of a milliliter (mL).
1 liter (L) = 1,000,000 μL
Precise pipetting is crucial for accurate experiments.
Pipettes use air displacement and disposable tips.
Pipette models vary in the minimum and maximum volumes they can measure. The maximum volume is often marked on the pipette.

Sample Preparation and Dilutions

Solutions: Mixtures of liquids, where one liquid(solvent) dissolves another (solute).
- Aqueous solutions use water as the solvent.
Solution Concentration: Amount of solute per unit of solution, expressed as mass or volume.
Concentration Units:
- Percent by mass (% w/w): grams of solute per 100 grams of solution.
- Percent by volume (% v/v): milliliters of solute per 100 milliliters of solution.
- Percent weight by volume (% w/v): grams of solute per 100 milliliters of solution.
- Molarity (M): moles of solute per liter of solution.

Dilution Formula

C₁V₁ = C₂V₂ (important!)
- C₁ = Initial concentration
- V₁ = Initial volume
- C₂ = Final concentration
- V₂ = Final volume
Ensure units (e.g., mL, L) are consistent.

Experimental Procedure

The lab exercises involve precise measurements using micropipettes (e.g., P1000, P200, P10).
Tables are provided to record measurements.
Students need to understand measuring procedures using different pipettes with different capacities and precision values, along with important concentration measures (e.g., molarity).

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Description

This quiz covers the essential techniques of pipette use and the concepts of sample preparation and dilutions in a laboratory setting. It explores the importance of precise pipetting for accurate results and the various types of solutions and their concentrations. Test your knowledge on the principles and practices of handling small liquid volumes in experiments.