Safety & Gear
What should you do immediately if a chemical splashes into your eyes during a lab activity?
Use the eyewash station immediately for 10 minutes.
When reading liquid volume in a graduated cylinder, where exactly do you align your eye level?
Read at the bottom of the meniscus.
Convert 34 meters (m) to centimeters (cm).
3,400 cm
State the formula for calculating density, including its standard units.
Density = Mass / Volume (D = m / V)
Units: g/mL or g/cm³
State the equation used to calculate Percent Error.
Percent Error =
| Experimental - Accepted | / Accepted × 100%
Compare glassware: Which piece of equipment is used for exact volume measuring vs approximate measuring?
Graduated Cylinder = Exact Measuring
Beakers / Erlenmeyer Flasks = Approximate Measuring
How many uncertain (estimated) digits should be included in any recorded measurement?
1 uncertain digit
What mnemonic phrase is commonly used to remember metric system conversion prefixes?
"King Henry Died By Drinking Chocolate Milk"
(Kilo, Hecto, Deka, Base, Deci, Centi, Milli)
A solid block has a mass of 70 grams and a density of 1.5 g/mL. What is the volume of the block?
Volume = 46.7 mL
(Calculation: Volume = Mass / Density = 70 g / 1.5 g/mL)
Differentiate between "Accuracy" and "Precision" in lab data collection.
Accuracy = Closeness to true target value.
Precision = Closeness of repeated measurements to each other.
State two basic rules regarding personal attire and hair before starting a chemistry lab experiment.
Tie back long hair & wear closed-toe shoes
(along with wearing safety goggles)
A ruler is marked to the tenth of a centimeter (0.1 cm). Which reading is acceptable: 6 cm, 6.1 cm, 6.10 cm, or 6.101 cm?
c) 6.10 cm
(Certain digit in tenths + 1 estimated digit in hundredths)
Convert 2.5 kg to grams AND 250 mL to liters.
2.5 kg = 2,500 g
250 mL = 0.25 L
An object has a density of 0.85 g/mL. Will it float or sink when placed in pure water (density = 1.0 g/mL)? Explain.
It will FLOAT. Objects float when their density (0.85 g/mL) is less than water's density (1.0 g/mL).
A student calculates density as 6.50 g/mL. If the accepted density is 6.95 g/mL, calculate the percent error.
| 6.50 - 6.95 | / 6.95 × 100% = 6.47%
Which lab tool would you select to measure out precisely 15.4 mL of liquid solution? must give specific size.
A 25 mL Graduated Cylinder
A cylinder is marked to the tenths place. Roger records 2.19 mL. Melissa records 2.199 mL. Who is correct and why?
Roger is correct (2.19 mL).
Marked to tenths (0.1) → read to hundredths (0.01) with 1 estimated digit. Melissa estimated 2 digits!
Which measurement is LARGER: 12 dg (decigrams) or 12 dag (decagrams)?
12 dag is LARGER
(12 dag = 120 g, whereas 12 dg = 1.2 g)
A metal sample has a mass of 13.9 grams and occupies a volume of 2.0 mL. Calculate its density.
6.95 g/mL
(13.9 g / 2.0 mL = 6.95 g/mL)
A line has an actual length of 76.49 cm. A student measures: 76.48 cm, 76.47 cm, and 76.49 cm. Are these accurate? Precise?
BOTH. Accurate because values are near 76.49 cm; Precise because repeated trials are within 0.02 cm of each other.
What is the correct protocol if glassware breaks during a lab experiment?
Notify teacher immediately and dispose in designated broken glass container.
Explain the difference between "certain digits" and "uncertain digits" when reading an instrument.
Certain digits match printed scale lines exactly.
Uncertain digit is the single estimated value between lines.
Identify the best metric units/prefixes to measure: a) mass of a peanut and b) volume of water in a bathtub.
a) Mass of peanut = Milligrams (mg) or Grams (g)
b) Bathtub water = Liters (L) or Kiloliters (kL)
How does particle arrangement differ between a high-density substance and a low-density substance of identical volume?
High-density substances have particles packed more closely together (more mass in equal volume).
Which type of error is "fixable" , systematic or random?
Systematic - these errors are identifiable and, once identified, they can be eliminated for future experiments