Prior to the discovery that freon-12 (cf 2 cl 2 ) was harmful to the earth’s ozone layer, it was frequently used as the dispersing agent in spray cans for hair spray, etc. its enthalpy of vaporization at its normal boiling point of − 29.2°c is 20.25 kj mol − 1 . estimate the pressure that a can of hair spray using freon-12 had to withstand at 40°c, the temperature of a can that has been standing in sunlight. assume that ∆ vap h is a constant over the temperature range involved and equal to its value at − 29.2°c.

Scientists often have to deal with numbers that are either very large or very small. for example, the radius of the sun is approximately 696,000 kilometers, while bacterial cells are as small as 1.9 × 10-4 millimeters. express each number in an alternate form.

For a family dinner, jose’s mom baked a loaf of bread. during the meal, his grandmother commented, “this bread is so dense! ” what do you think his grandmother meant by the word dense? you have some ideas regarding density already, but this experiment will enrich your understanding of the relationship between mass, volume and the density of objects. when making measurements in this experiment we will be using si units, the international system of units. the purpose of using si units is to have the ability to communicate and compare data results with other experiments without having to make conversions. measurement symbol si unit length m meter mass kg kilogram volume l liters density kg/l kilograms per liter any calculations that are performed during this experiment will ultimately be reported in scientific notation. recall that scientific notation is extremely important when we have data that is extremely small or large. scientists rely on a standard form of communication to quickly make hypotheses and judgements based on data. what is the density of block a? a0kg/l what is the density of block b? a1kg/l what is the density of block c? a2kg/l what is the density of block d? a3kg/l what is the density of block e? a4kg/l which block is the densest? a5

Salt in oceans comes from and of rocks