Lecture_2_-_sig_figs__dimensional_analysis

What is included in every measurement in Chem 102?

A number and a unit.

What does precision refer to in measurements?

Closeness of measurements to each other; reproducibility.

What is the difference between accuracy and precision?

Accuracy indicates closeness to the accepted value, while precision refers to the reproducibility of the measurements.

Define significant figures in the context of measurements.

The number of digits in a measurement that reflects the degree of uncertainty; more digits indicate less relative uncertainty.

What is the significance of zeros on the left in significant figures?

Zeros on the left are not significant.

What do zeros on the right signify in measurements?

Zeros on the right are only significant if there is a decimal point present.

When performing multiplication or division with significant figures, how is the number of significant figures in the final answer determined?

It is dictated by the number with the fewest significant figures in the calculation.

What should be done when performing multiple calculations involving significant figures?

Always carry at least one extra significant figure in intermediate answers, then round to the correct number of significant figures at the end.

What does dimensional analysis focus on during calculations?

It focuses on units crossing off when setting up a calculation.

What are unit factors in dimensional analysis?

Unit factors are expressed as fractions to facilitate unit conversions.

How do you calculate density?

Density = mass/volume.

What is the volume displacement method for measuring volume?

The increase in the volume of liquid when an object is submerged.

How many significant figures should be noted in the final calculation of a density problem where mass is 12.4303 g and volume is 5.1 mL?

Two significant figures due to the two sig figs in the volume value.

What unit is used for mass in the SI system?

Kilogram (kg).

What does the prefix 'milli' represent in the SI system?

0.001 or 10^-3.

What does the law of significant figures state?

The uncertainty in final calculations can be no better than the uncertainty in the numbers used.

What is the typical uncertainty assumed in the last digit of a measurement?

±1.

What is the relationship between actual density and percent error concerning experimental results?

Percent error is calculated based on the difference between experimental value and actual value.

When should you round a number up, according to significant figures rules?

Round up if the digit to the right is 5 or greater.

How do you express unit conversions in dimensional analysis?

As fractions called unit factors.