Presentation on theme: "How do you calculate the density of a substance?"— Presentation transcript:
1 How do you calculate the density of a substance? Density CalculationsHow do you calculate the density of a substance?
2 Covered in This LessonThis lesson will demonstrate how to calculate density to the correct number of significant figures(sig figs) using experimental measurements.When calculating density we measure the mass and the volume of the sample.The volume can be measured using one of several methods.
3 Density Formual V When calculating density you measure the mass of the sample using a balancevolume of the sample from one of the methodsapply the formula: mass/volume = densityorm = dV
4 Methods: VolumeThere are three methods to measure the volume of a substance. The method used is determined by the type of substance.Methods for the;volume of liquidvolume of regular solidvolume of irregular solid.
5 Volume of a LiquidIf the substance is a liquid, measure it directly in a graduated cylinder.
6 Examples 1If a liquid sample has a mass of 4.83 g and a volume of 2.7 mL what is its density.4.83 g =2.7 mLBecause 2.7 has 2 sig figsthe final answer is 1.8 g/mL
7 Volume of a Regular Solid If you have a regular solid like a cylinder, cube, or rectangular solid measure the dimensions needed and apply the volume formula.
8 Examples 2If cubic solid sample has a mass of g and the side is 2.55 cm, what is its density.V = s3 = (2.55 cm) 3 = cm3D = g =cm3Because 2.55 has 3 sig figsthe final answer is 2.44 g/cm3
9 Volume of a Irregular Solid If you have an irregular solid use displacement, take initial volume of water in a graduated flask, submerging the sample in the flask, and take the final volume while the solid is submerged. Subtract final volume minus initial volume.
10 Examples 3Find the density of a solid sample with a mass of g and displacement is used to find the volume, the initial volume is mL, the final volume is mL.V = mL – mL = 53.18mL75.45 g = g/mL53.18mLSince both mass and volume have 4 sig figsthe final answer is g/mL
11 Practice ProblemsFind the density of a liquid with a volume of 3.8 mL and a mass of 3.75 g.Find the density of a rectangular solid with a length of 4.5 cm, a width of 2.5 cm, a height of 1.5 cm and a mass of g.Find the density of an irregular solid with a mass of 1.2 g, an initial volume of 25.7 mL and final volume of 18.4 mL when displacement is used.
12 Answers Practice Problems Density = g/mLDensity = 2.79 g/cm3Density = 8.8 g/mL