Measurements and Lab Equipment (Obj 2:a-b; 3)

Measurement What is a measurement? A measurement is a quantity that has both a number and a unit. How are measurements used in science? To collect data and to keep track of the amounts being used

Units (don’t need to write) What is a unit? Units are standard values Why do we use units? Units allow people to be able to compare data and to be consistent

Types of Measurements Qualitative measurements deal with observations or “qualities”. Quantitative measurements deal with numbers or “quantities”.

Types of Measurements Label the following as quantitative or qualitative A wooden block is 1 foot in length A wooden block is red in color The solution is blue The solution is 321 mL in volume quant qual qual quant

Making Quantitative Measurements A quantitative measurement should have both a number and unit. When making the measurement you write down the known digits plus one that is estimated In the measurement 12.49 cm the 12.4 are known and the 9 is estimated

Measurement (don’t need to write) Every experimental measurement has a degree of uncertainty. The volume, V, at right is certain in the 10’s place, 10mL<V<20mL The 1’s digit is also certain, 17mL<V<18mL A best guess is needed for the tenths place.

Measurement (cont) Three differently calibrated meter sticks are used to measure the length of a board. a) A meter stick calibrated in a 1-m interval. b) A meter stick calibrated in 0.1-m intervals. c) A meter stick calibrated in 0.01-m intervals. Measuring How many significant figures are reported in each measurement?

Measurement (cont) What is the Length? We can see the markings between 1.6-1.7cm We can’t see the markings between the .6-.7 We must guess between .6 & .7 We record 1.67 cm as our measurement The last digit 7 was an estimate but all three numbers are still part of the measurement

Measurement (cont) What is the length of the wooden stick? 1) 4.5 cm

Lab Equipment Match the following to the proper measuring tool Temperature Mass Density Volume Graduated cylinder Scale/balance Scale/balance and ruler Thermometer Answer Key: 1 = D, 2 = B, 3 = C, 4 = A

Lab Equipment Match the following to the proper measuring tool 1. 2. 3. 4. Beaker Scale/balance Hot plate Thermometer Answer Key: 1 = D, 2 = A, 3 = B, 4 = C