Chemistry (V1)
No description yet. This curated deck is ready for daily study.
Card preview (24)
States of Matter
Describe the intermolecular forces, arrangement, motion, and compressibility of a solid
Very strong intermolecular forces of attraction, tightly packed and regularly arranged, vibrate in fixed positions, incompressible
Describe the intermolecular forces, arrangement, motion, and compressibility of a liquid
Intermediate intermolecular forces of attraction, closely packed and irregularly arranged, slide past each other, incompressible
Describe the intermolecular forces, arrangement, motion, and compressibility of a gas
Very weak/non-existent intermolecular forces of attraction, far apart and irregularly arranged, quickly, randomly, freely moving in all directions, compressible
Describe the 4 main changes in state
Melting: solid to liquid Freezing: liquid to solid Boiling/evaporation: liquid to gas Condensation: gas to liquid
What is sublimation
The direct change of a substance from solid state to gas state without passing through liquid state
Explain how changes of state occur
As particles of a substance are heated, they gain kinetic energy move more and overcome attractive forces; when they are cooled, they lose kinetic energy and form attractive forces. When a certain temp. is reached the substance changes state
What are melting and boiling points?
They are the temps. at which changes of state occur
What is the difference between the melting and boiling points of pure and impure substances?
Pure substances: have sharp defined melting and boiling points Impure substances: have a range of melting and boiling points (usually lower melting point and higher boiling point)
Diffusion
What is diffusion?
The spreading out of particles in a gas or liquid from an area of high to lower concentration until evenly spread. Diffusion cannot happen in a solid; it must dissolve before diffusing.
What factors affect diffusion?
• Temperature • concentration gradient • Molecular weight (Mr) of the compound. As temperature increases, the diffusion rate increases; as molecular weight increases, the diffusion rate decreases.
What happens in the white ring experiment?
Vapours from soaked cotton diffuse and move towards the center of the tube, forming a white ring of ammonium chloride (NH4Cl) nearer to the HCl cotton. NH3 (Mr = 17) moves faster than HCl (Mr = 36.5) due to its lower molecular weight.
What type of reaction occurs between HCl and NH3 in the white ring experiment?
Neutralization reaction. This reaction can be reversed by heating ammonium chloride.
What occurs during the thermal decomposition of ammonium chloride?
Ammonium chloride is thermally decomposed, releasing a mixture of hydrogen chloride and ammonia gas. The chemicals react again to form ammonium chloride at the exit of the test tube.
What is the mixture of gases in the center of the test tube during the experiment?
Hydrogen chloride and ammonia. These gases react to form ammonium chloride.
Why does the experiment take a few minutes despite gases traveling rapidly?
Because gases do not travel in straight lines and collide with particles already in the test tube.
What is the chemical name for HCl when in liquid form?
Hydrochloric acid. In gas form, it is referred to as hydrogen chloride.
Solubility
What is solubility?
The amount of solute that can dissolve in a solvent at a certain volume and temperature (given in the units g/100g of solvent) By definition, it is the maximum mass (g) that can dissolve in 100g of solvent.
How does temperature affect solubility?
Solubility increases with temperature As temperature increases, there are wider intermolecular spaces, allowing more solid to dissolve.
How does pressure affect the solubility of gases?
Solubility of gases increases with pressure As pressure increases, gases become more soluble.
Define solute.
A substance that dissolves in a solvent.
Define solvent.
What the solute dissolves in.