Chemistry Lab: Molarity Calculation
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Questions and Answers

A beaker can be used to accurately measure the volume of a liquid.

False

What is the main purpose of a bulb pipette?

  • To measure the volume of a flask
  • To temporarily store solutions or solvents
  • To store liquid solvents or solutions
  • To transfer very precise volumes from one container to another (correct)
  • What is the unit of molar concentration?

    mol/L

    The concentration of a chemical substance or compound in a solution is often given in ______________, or mol/L.

    <p>moles per liter</p> Signup and view all the answers

    What is the name of the device used to measure the mass of a substance?

    <p>Analytical balance</p> Signup and view all the answers

    Match the following laboratory equipment with their purposes:

    <p>Bulb pipette = To transfer very precise volumes from one container to another Measuring cylinder = To measure the volume of a liquid Beaker = To temporarily store solutions or solvents Analytical balance = To measure the mass of a substance</p> Signup and view all the answers

    A blue-capped bottle is used to measure the volume of a flask.

    <p>False</p> Signup and view all the answers

    What is the molar mass of NaCl (table salt)?

    <p>58.44 g/mol</p> Signup and view all the answers

    What is the purpose of a volumetric flask in a chemistry lab?

    <p>To create solutions with a high accuracy of concentration</p> Signup and view all the answers

    Molar mass is defined as the mass of 0.5 mol of a pure substance expressed in grams.

    <p>False</p> Signup and view all the answers

    What is the formula to find the molarity of a solution?

    <p>C=n/V</p> Signup and view all the answers

    The relationship between mass and amount in mol for any chemical substance is governed by its _______________________.

    <p>molar mass</p> Signup and view all the answers

    What is the instrument of high precision used to obtain just the right amount of substance?

    <p>Analytical Balance</p> Signup and view all the answers

    A volumetric flask comes with a stopper to seal off the flask for mixing.

    <p>True</p> Signup and view all the answers

    The symbol for amount in moles is _______________________.

    <p>n</p> Signup and view all the answers

    Match the following laboratory equipment with their descriptions:

    <p>Analytical Balance = Instrument of high precision to obtain just the right amount of substance Volumetric Flask = Standard piece of glassware to create solutions with a high accuracy of concentration Pipette = Device used to measure and transfer small volumes of liquid</p> Signup and view all the answers

    What is the purpose of a micropipette?

    <p>To transfer small amounts (&lt; 1 ml) of liquids</p> Signup and view all the answers

    The upper and lower limits of the micropipette should be exceeded when using it.

    <p>False</p> Signup and view all the answers

    What is the formula for molarity?

    <p>M = n/V</p> Signup and view all the answers

    The concentration of a chemical substance or compound in a solution is often given in ______________ per liter.

    <p>moles</p> Signup and view all the answers

    How many moles are in 15 grams of lithium?

    <p>0.25 moles</p> Signup and view all the answers

    A micropipette is used to weigh small amounts of solids.

    <p>False</p> Signup and view all the answers

    Match the following equipment with their uses:

    <p>Micropipette = To transfer small amounts of liquids Measuring Cylinder = To measure the volume of a solution Analytical Balance = To weigh small amounts of solids Pipette = To transfer large amounts of liquids</p> Signup and view all the answers

    Study Notes

    Laboratory Equipment and Procedures

    • An analytical balance is used to obtain precise amounts of substances.
    • Glassware is used for quantitative transfer and solution preparation.

    Volumetric Flask

    • A standard piece of glassware in a chemistry lab.
    • Used for creating solutions with high accuracy of concentration.
    • Has a single calibration mark and a stopper for sealing.

    Mass and Moles Conversions

    • The relationship between mass and amount in moles is governed by molar mass.
    • Molar mass is defined as the mass of 1 mole of a pure substance expressed in grams.
    • Symbols and units: mass [g] = m, amount [mol] = n, molar mass [g/mol] = M.

    Examples of Mass and Moles Conversions

    • NaCl (table salt) has a molar mass of 58.44 g/mol.
    • H₂O (water) has a molar mass of 18.02 g/mol.

    Molar Concentration

    • Concentration of a chemical substance or compound in a solution is often given in moles per liter, or mol/L.
    • Molarity is represented by the symbol M and is calculated by dividing the amount in moles (n) by the volume in liters (V): M = n/V.

    Other Laboratory Equipment

    • Beaker: used for temporarily storing solutions or solvents.
    • Blue-capped bottle: used for storing liquid solvents or solutions.
    • Bulb pipette: used for transferring very precise volumes from one container to another.
    • Measuring cylinder: used for transferring small amounts of liquids.

    Micropipette

    • Used for transferring small amounts (< 1 ml) of liquids.
    • Identified by the number near the display window.
    • Steps to follow when using the micropipette: select the volume, set the tip, and use appropriate tips.

    Sample Questions and Exercises

    • Examples of converting between mass and moles, and calculating molarity.
    • Remember to always select the smallest size pipette and use appropriate tips.

    Solution Preparation

    • Involves preparing an aqueous solution of a given molarity from a water-soluble salt.
    • Steps include determining the exact amount of salt needed, using an analytical balance, and preparing the solution using a volumetric flask.

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    Description

    In this quiz, you will practice calculating molarity in a chemistry lab setting. You'll use analytical balances to measure substances and apply the formula to find molarity. Take your time and get it right!

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