23 Questions
A beaker can be used to accurately measure the volume of a liquid.
False
What is the main purpose of a bulb pipette?
To transfer very precise volumes from one container to another
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.
moles per liter
What is the name of the device used to measure the mass of a substance?
Analytical balance
Match the following laboratory equipment with their purposes:
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
A blue-capped bottle is used to measure the volume of a flask.
False
What is the molar mass of NaCl (table salt)?
58.44 g/mol
What is the purpose of a volumetric flask in a chemistry lab?
To create solutions with a high accuracy of concentration
Molar mass is defined as the mass of 0.5 mol of a pure substance expressed in grams.
False
What is the formula to find the molarity of a solution?
C=n/V
The relationship between mass and amount in mol for any chemical substance is governed by its _______________________.
molar mass
What is the instrument of high precision used to obtain just the right amount of substance?
Analytical Balance
A volumetric flask comes with a stopper to seal off the flask for mixing.
True
The symbol for amount in moles is _______________________.
n
Match the following laboratory equipment with their descriptions:
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
What is the purpose of a micropipette?
To transfer small amounts (< 1 ml) of liquids
The upper and lower limits of the micropipette should be exceeded when using it.
False
What is the formula for molarity?
M = n/V
The concentration of a chemical substance or compound in a solution is often given in ______________ per liter.
moles
How many moles are in 15 grams of lithium?
0.25 moles
A micropipette is used to weigh small amounts of solids.
False
Match the following equipment with their uses:
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
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.
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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