Chemistry Lab Safety and Equipment

Flashcards covering key concepts from a chemistry lab safety and equipment lecture.

Where do you find information about the accuracy of individual glassware?

On the glassware itself.

A graduated cylinder is always the least accurate glassware. True or false?

False, a beaker is the least accurate.

Which glassware would you use to make a 1.2 mM solution?

Use a volumetric flask and weigh out a large amount.

It is always best to use an analytical balance. True or false?

False, you don’t always need precise amounts.

A graduated pipette is calibrated to the volume it releases. True or false?

True, don’t push the last bit out of the tip.

All graduated cylinders have the same accuracy. True or false?

False.

How many decimal places do you need to indicate for a volumetric flask?

One decimal place (e.g., 100.0 mL, 250.0 mL), except for the 1.00 L flask.

How many grams of KCl do you need to add to make a 50 mL solution of 1 mM?

3.528 g.

When mixing solutions, do you add an acid to water or water to acid?

Add acid to water to prevent splashes and dangerous reactions.

What should you do to care for minor cuts in the lab?

Wash with cold water to remove glass slivers and chemicals.

What should be applied to prevent bleeding in the case of major cuts?

Apply a pressure bandage, elevate the wound, and keep the person warm.

What to do if your clothes are catching on fire?

STOP, DROP, and ROLL.

Where do you find information about potential hazards of a substance?

The MSDS on the reagent label (Material Safety Data Sheet).

What does the 'meniscus' refer to in an analytical laboratory?

The curvature shape liquid takes on at the very bottom.

A burette is accurate to how many decimal places?

To two decimal places, estimating the second decimal value is true.

What is a primary standard?

A substance with a known concentration used to measure the concentration of another substance.

What is the difference between accuracy and precision?

Accuracy is how close you are to the true value; precision is how close each measurement is.

Is it okay to neglect a measurement point if it doesn’t 'fit'? True or false?

False; use the Grubbs test if you have more than 4 data points.

Name three examples for personal protective equipment.

Lab coat, lab goggles, and nitrile gloves.

What might cause inaccuracies during titrations?

Inconsistent meniscus level, incomplete dissolving of standard, inconsistent end-point color reading, inconsistent levels of indicator, filling burette above 0.0 mL mark, parallax error.

What might cause inaccuracies during making a solution?

Not weighing substance properly, incomplete transfer of weighed substance, overflowing calibration marks, not heating the solution properly.

Name experimental steps that can be performed outside the fume hood.

Addition of KI to copper sample, addition of starch indicator, all titrations, extraction of capsaicin into ABS ethanol.

Name experimental steps that must never be performed outside the fume hood.

Boiling of acids (e.g., HNO3).

How does a potentiostat work?

It controls the current between the working electrode and counter electrode, affecting the potential.

What is the purpose of a reference electrode?

It provides a reference for the potential created at the working electrode.

What is a redox reaction?

Transfer of electrons in a reaction.

Is the electrochemical current proportional to the number of molecules converted at the working electrode? True or false?

True.

What can a cyclic voltammogram tell you?

Reversibility of a species and concentration of a species.

How does the standard addition method work?

A specific method for quantifying analytes by adding known quantities of the standard to the sample.

True or false: A blank reading needs to be taken between every absorbance measurement using a spectrophotometer.

True.

How should you measure hygroscopic reagents in your weighing bottle? True or false?

False; weigh the capped bottle and extract the compound.

What is direct weighing?

Placing your sample vial on the balance, taring, then adding the substance directly to prevent sample loss.