density problems.

First recall that the units of density are g/cm3 or g.cm-3.

A student found that 20.0 mL of a liquid weighed 35.987 g. What is its density?

 

 

 

 

 

 


Using a jewelers balance a student found that a coin weighed 2.34 carats in air. By weighing it again submerged in water she found it had a volume of 0.034 mL. What is its density? (1 carat = 200 mg, defined)

 

 

 

 

 

 

 

 

 

 

 

pressure problem.

What is the force in Newtons on the surface of water in a 10.00 x 10.00 cm square container (area = 100.0 cm2) if the pressure is 754 mmHg?

 

 

 

 

 

Dalton's atomic theory

  1. All matter is composed of ultimately small particles, called atoms.

  2. Atoms are permanent and indivisible - they can neither be created nor destroyed.

  3. Elements are characterized by their atoms. All atoms of a given element are identical in all respects. Atoms of different elements have different properties.

  4. Chemical change consists of a combination, separation, or rearrangement of atoms.

  5. Chemical compounds are composed of atoms of two or more elements in fixed ratios.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Atoms are now known to consist of three different types of particles: electrons, protons and neutrons

 Particle Charge Relative Mass Mass
Electron (e-) -1 1/1840 9.11 x 10-28g
Proton (p or H+) +1 ª1 1.67 x 10-24g
Neutron (n) 0  ª1  1.67 x 10-24g

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

© R A Paselk

Last modified 1 September 2009