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Reacting Acids and Bases. On the way to neutralization. What happens when acids and bases are mixed?. Neutralization These reactions are often new compounds in solution Example: H Br ( aq ) + Na OH ( aq ) H 2 O (l) + NaBr ( aq )
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Reacting Acids and Bases On the way to neutralization
What happens when acids and bases are mixed? • Neutralization • These reactions are often new compounds in solution Example: HBr(aq) + NaOH(aq) H2O(l) + NaBr(aq) Acid Base results in water and a salt
Mixing • Adding an acid to a base slowly consumes the base • When all the base is reacted (consumed/used up) the solution is considered neutralized • A salt and water remains • The solution is now neither acidic nor basic
What is a Salt? • A compound made up of both positive and negative ions HBr(aq) + NaOH(aq) H2O(l) + NaBr(aq) Acid Base results in water and a salt
What happens now… • If any more acid is added at this point the solution then becomes more acidic • These changes can be seen by using a universal indicator Universal indicator: change many colours as pH changes An indicator that changes colour as soon as all the base is consumed can also be used
Qualitative Neutralization • Mixing approximate amounts of acid and base • Cleaning chemical spills - using baking soda to clean an acid spill • The amount of baking soda doesn’t matter as long as the spill is neutralized
Quantitative Neutralization • This is a process called titration • The chemist mixes exact amounts of acid and base to identify when the solution hits the neutralization point
Looking further at Neutralization • Neutralization reactions are special forms of double displacement reactions Example: HCl(aq) + NaOH(aq) H2O(l) + NaCl(aq)
What happens: • The hydrogen ion from the acid reacts with the hydroxide ion resulting in… Water H+ + OH- H2O
What can we use acid/base reactions for? • Hair dressers use these reactions in order to perm or straighten hair • The hair curling solution is a base • It changes the structure of the hair • Allowing it to accept or undo a curl • Applying the neutralizer solution stops the process • Allowing the hair structure to reform, maintaining its new shape
Where else? • Fire extinguishers… Sulfuric acid and sodium bicarbonate react creating large amounts of foam bubbles (CO2), which smother the flames
Read:Nelson • Acid-Base reactions in the home • Acid-Base reactions in baking • Antacids • Found on pg 318 – 319 • Acid Deposition page 116-118
Read:MHR • Acid-Base reactions Antacid • Acid-Base reactions Acid Spills • Acid-Base reactions – Acid Precipitation • Acid-Base reactions – Renewing Acidified Lakes • Acid-Base reactions – Acid Leaching and Metals • Found on pg 236 - 246