Water solubility and concentration Flashcards
Wat is the shape of a water molecule and what type of bonds does it have
A water molecule has a bent V shape and contains 2 polar covalent bonds
What are the forces that attract one water molecule to another
Relatively strong hydrogen bonds
How many hydrogen bonds can a single water molecule make with other water molecules
4 hydrogen bonds in ice
What gives water its high melting/boiling points
The strength of the hydrogen bonds, and
consequently the large amounts of energy required to disrupt the hydrogen bonds compared to other discrete molecules
Identify and explain the patter of melting points down the group 16 hydrides
Except water, the melting point increases down the group 16 hydrides, due to increasing strength of dispersion forces
Why is ice less dense than water
Due to its unique geometric arrangement of water molecules as a result of hydrogen bonding
What is Heat capacity and what does it measure
Heat capacity is a measure of a substance’s capacity to absorb and store heat energy, and measures The quantity of energy in joules to increase the temperature of 1 gram of a substance by 1 degree
Why is a heat capacity of water relatively high
The ability of the hydrogen bonds between water molecules to absorb and store heat energy
Equation for the heat energy required to increase a mass of a substance by a particular temperature
q=mc ΔT
what is q in q=mc ΔT
the heat energy
what is m in q=mc ΔT
The mass in grams
what is c in q=mc ΔT
C is the specific heat capacity
what is ΔT in q=mc ΔT
The change in temperature
What is latent heat
The energy or heat released or absorbed during a phase change of a material
What type of process is the conversion of gas to liquid
Exothermic
What type of process is the conversion of ice to water
Endothermic
What is the latent heat of vaporisation of a substance
The heat energy needed to change 1 mole of the substance from a liquid to a gas at its boiling point
What is the latent heat of fusion of a substance
The heat energy needed to change one mole of a substance from a solid to a liquid at its boiling point
What equation is used to determine the heat energy requried to change the state of a substance
q= n x L
heat energy = amount(mol) x Latent heat
Why does the relatively high latent heat of vaporisation of water have significance
For cooling of organisms and preservation of water supplies
What effect do oceans have on global temperatures
The oceans have a buffering effect on global temperatures
What is a precipitation reaction
A reaction between 2 soluble salts (aqueous salts) that produces an insoluble salt
What is solubility
A measure of how much solute will dissolve in a given amount of solvent at a specified temperature
What happens to the solubility of solids and gases are the temperature of a solution increases
The solubility of solids increase
the solubility of gases generally decrease
What is the term given to a value that lies on the solubility curve
Saturated solution
What is the term given to a value that lies under the solubility curve
Unsaturated solution
What is the term given to a value that lies above the solubility curve
Supersaturated solution
Why do gases become less soluble as temperatures increase
As the dispersion forces between gas and water are easily broken at hgih temperatures
What is the term given to liquids that dissolve in a solvent
(e.g. H20)
Miscible
What is the term given to liquids that don’t dissolve in water
e.g. Oil
Form a layer and a called immiscible
Factors that affect solubility
Hydrogen bonding
Attraction between solute particles
Temperature
(for gases, pressure and temperature)
What is concentration of a solution
solute and solution
The quantity of solute dissolved in a quantity of solution
Molarity
The number of moles of solute per litre of solution
Formula for molar concentration
c=n/V
Symbol for Molar
M
Alternative units of concentration
Grams per litre
Parts per million
Percentage mass for mass
Percentage mass for volume
What is ppm
formula
1mg per 1L
Formula for Dilution
C2= (C1 x V1) / V2
Conjugated base
An acid which has donated a proton (H+)
Conjugated Acid
A base that has accepted a proton
What is the Bronsted-Lowry theory
Describes acids as proton donors and bases are defined as proton acceptors
Monoprotic
Acids that only have one proton to donate
e.g. HCl, HNO3
Diprotic
Acids that have 2 protons to donate
Triprotic
Acids that have 3 protons to donate
Amphiprotic
Describes substances that can behave as either an acid or a base depending on what substance it is reacting with
Why does water have a high latent heat
Large amounts of energy is needed to break the Hydrogen bonds so that the state can change
What are the 3 key features of water
1) Has a relatively high melting point and boiling point
2)Has a high latent heat of fusion/vaporisation
3)Has a high specific heat capacity
Why does ice expand when frozen
When water freezes each H20 molecule form 4 hydrogen bonds with 4 other h20 molecules, thus producing an open structure compound with liquid water where the molecules are sliding over each other.
