Chem 32 ch.7

Substances that can donate an H+ atom to some other molecule are called acids. If you put HCl into water ( H2O ) the HCl will give its H to H2O to create Cl- and H3O+, so, HCl is an acid.

Acids are sometimes called "proton donors".

Compounds tha form hydroxide ions when they dissolve in water are bases.

When an ionic compound like NaOH dissolves in water it breaks up into Na+ and OH-, the OH- is a hydroxide ion, so NaOH is a base.

H3O.

The ion product ( product as in multiplication ) of water is the relationship of H3O+ and HO- in any aqueous ( water based ) solution.

The molarity of H3O+ in the solution times the molarity of HO- in the solution will equal 1 x 10^-14.

molarity of H3O+ x molarity of OH- = 1x10^-14

( square brackets around a compound mean that the formula is talking about the molarity of the compound in the brackets... )

[H3O+] x [HO-] = 1 x 10^-14

[H3O+] x [HO-] = 1x10^-14

.02 x ??? = 1x10^-14

1x10^-14 / .02 = 5x10^-13M

pH is a measurement of how much H3O+ is in an aqueous solution.

It starts with a measurement of moles per liter ( molarity, M ) of H3O+ in an aqueous solution.

If the molarity of H3O+ in a solution is 10^-3M then the pH of the solution is simply 3.

If the molarity of H3O+ in a solution is 10^-9 then the pH of the solution is 9.

[H3O+] x [OH-] = 10^-14 So when pH is 7 there are equal amounts of H3O+ and OH-.

A high pH, like pH 10, would mean the M of H3O+ in the solution is 10^-10, which is a smaller number than say 10^-4.

So, a low ( lower than 7 ) pH has more H3O+ in it than HO-. So a low pH, means more H3O+ than HO-, means acidic.

High ph ( higher than 7 ) means less H3O+, more OH-, means more basic, less acidic.

More acidic.

Lower than 7 ph.

More basic.

Higher than 7 ph.

All aqueous solutions have some water in them ( it's what makes them aqueous! ) and since there is some amount of self ionization in water, all aqueous have some amount of H3O+

Acidic.

neutral.

basic.

or, alkaline.

A chemical reaction that results in ions as products.

All common acids are made up of molecular compounds, made up of non-metalic atoms held together with covalent bonds.

All acids form ions when they dissolve in water, therefore all acids are electrolytes.

Also called a "strong acid". An acid is a strong electrolyte when many of its molecules donate an H+ to other molecules. The more easily a compound's molecules ionize ( break up into ions ) in a solution, the more ions it produces as products and the better it conducts electricity.

All strong acids ionize completely.

Also called a "weak acid". An acid is a weak electrolyte when the molecules that make it up do not give very many H+ protons to other molecules in a solution. In this case, not as many molecules ionize ( break up into ions ) as a product and the solution does not conduct electricity well.

Weak acids ionize in range ability to ionize. Some weak acids ionize more than other weak acids.

An acid's ability to donate a proton. A strong acid has a high "strength of acid" and donates H+ atoms more easily. Weak acids have a low "strength of acid" and do not donate H+ protons so easily.

• Remember:
• strong acid = low pH = more acidic

weak acid = high pH = less acidic

A hydroxyl group is a H atom covalently bonded to an O atom, it is a polar bond with H being positive and O being negative, like in water.

It must have at least one hydroxyl group, one H covalently bonded to an O. The atom that this O is bonded to will usually have another O bonded to it. H---O---X---O

HOXO!

Strong acids ionize completely. So if you put .1 moles of a strong acid into water the acid/water solution will have .1mols of H3O+ because every one of the acid molecules will have given a H+ to a water molecule.

Any substance that can remove a hydrogen proton from a water molecule is a base.

Or

Any compound that can bond to H⁺.

Bases always produce hydroxide ions when they dissolve in water. This causes the amount of OH- ( hydroxide ions ) in the solution to increase. More OH- means more basic, means higher pH.

Most anions ( negatively charged ions ) are bases. Phosphate for example, PO₄^3- is an anion, a negatively charged ion. It is a base.

Also, most molecules that have a nitrogen covalently bonded to a carbon, hydrogen, or both are bases.

In a strong base, every molecule of the base will pull a H+ from a water molecule when added to water.

acidic

basic.

Bases always produce hydroxide ions when dissolved in water.

it takes a H proton from a water molecule and leaves OH-, hydroxide, behind. More hydroxide in the solution raises the solution's pH.

Bases always have a pH above 7.

Hydroxide ( OH- ) itself is a strong base.

Sulfide ( S2- ) is a strong base.

When a reactant acid loses an H, it ends up as a product minus one H ( HSO₄ becomes SO_4, itself a base ). The two together are a conjugate pair. The reactant is the acid, the product is the conjugate base.

• HSO₄ + H₂O <---> SO₄^2- + H₃O⁺
• or
• When a reactant base without an H ends up as a product that has gained an H ( HPO₄^2-, a base becomes H₂PO₄^-, itself an acid ) the two are a conjugate pair. The reactant is the base, the product the conjugate acid.

HPO₄^2- + H₂O <---> H₂PO₄^- + OH^-

When an acid and a base are mixed together a proton ( H⁺ ) moves from the acid to the base.

All acid-base reactions are proton transfers. :)

When a hydrogen atom / proton / H+ moves from an acid to a base, it leaves the binding electrons behind.

The term amphiprotic refers to a compound that can act as an acid or a base, being able to either lose an H⁺ or gain an H⁺.

Negative ions ( anions ) that have an ionizable H+ ( an H+ proton that can come off to form an acid ) are usually amphiprotic substances.

7.35 - 7.45

Plasma pH below 6.8 causes death within seconds.

A buffer is a solution ( two or more compounds combined ) that resists a change in pH when an acid or base is added to it. A buffer must contain a substance that can neutralize acids and a substance that can neutralize bases.

Most buffers are solutions that contain a conjugate acid-base pair.