Density and SI Units Scientific Measurements SI Units

Density and SI Units

Scientific Measurements SI Units Significant Figures

SI Units Measurement system universal to scientists. Measurement standards (base and derived) Base unit— Quantity we can MEASURE Derived unit- Quantity provided by CALCULATION

SI Units (cont. ) Base Mass = kilogram (kg) Length = Meter (m) Time = Second (s) Temperature = Kelvin (°K) Derived Volume = m 3, we will use cm 3/ml ml is NOT an SI unit Density = kg/m 3, we will use g/cm 3 or g/ml

Mass vs. Weight What is the difference? How do we measure mass?

Density Physical property of matter/substances Used for substance identification Provides information on how solids/liquids interact Ratio of a substance’s mass and volume Density = Mass/Volume Units = SI Unit (kg/m 3), we will use g/cm 3 or g/ml

Example 1: A student obtains a mass of 5. 03 g for a metal and a volume of 3. 24 ml?

Example 2: What is the volume of a substance with a density of 0. 824 g/ml and a mass of 0. 451 g?

Example 3: A student records V 1= 2. 7 ml and V 2= 3. 4 ml after placing an object in a graduated cylinder. The mass of an empty beaker is 1. 13 g and the mass of both the beaker and substance is 4. 13 g. What is the object’s density?

Density Problems 1) An object has a mass of 4 grams and a volume of 1. 7 cm 3. What is it’s density? 2) What is an object’s mass if it’s density is 8. 3 g/cm 3 and the volume is 4 cm 3 ? 3) What is the volume of an object with a mass of 11 grams and a density of 4. 2 g/cm 3? 4) An object’s mass is found to be 40 grams. When this object is placed in a graduated cylinder with a V 1 of 17 ml, the V 2 becomes 20 ml. What is the object’s density?

Homework Density Problems