Chemistry

Physical and Chemical properties of Acids

Biola Emmanuel - Thu, 24th January, 2019 @ 17:08:41 PM

Topics in Chemistry

Salts and Types of Salt in Chemistry Separation Techniques Separation Techniques part 2 Separation Techniques part 3 Physical Change, Chemical Change, Element, Compound and Mixture Electrolysis, Electrolyte, Electrode, Anode and Cathode Grahams law of diffusion Physical Properties of Metals Daltons Atomic Theory and its Modifications Periodic table and Classification of Elements



Academic Questions in Chemistry

The only metal that exist as liquid at room temperature is _____.

  1. Nickel
  2. Duralumin
  3. Mercury
  4. Lead
  5. Titanium
  6. Cesium

ANSWER is Mercury

Mercury is a liquid metal at room temperature. Its chemical symbol is Hg. The name mercury comes from its Greek name, hydrargyrum, which means "liquid silver" .  Mercury has an atomic number of 80. Please read on the periodic table of elements here

The element mercury is also considered to be named after the fastest-moving planet in the solar system. You can read on solar system here.

Chemistry

What are Acids?

An acid is a substance that gives out hydrogen ion (H+) or hydronium ion (H3O+) or proton when dissolved in water. All acids usually contain or more of the positive H+ (cation) and an anionic group in their formular. For instance, the acid HCl (Hydrogen chloride) contains H+ as cation and Cl- as anions. The equation below explains our acid definition:

HCl(aq) + H2O(l) ---> H3O+(aq) + Cl-(g)

Note: cations are positively charged ions while anions are negatively charged ions.

 

Physical properties of acids

  1. They have sour taste (acid in latin means sour).
  2. They will turn a blue litmus paper to red.
  3. On a pH scale, they have a value less than 7 (The pH scale is used to measure the acidity or alkalinity of a subustance. It's values ranges from 0-14).
  4. They will change the color of methyl orange from orange/yellow to pink.
  5. They will change color of phenolphthalein from pink to colourless.
  6. They are corrosive, i.e they can rust metals and burn the human skin.
  7. Aqueous form of acids can conduct electricity.

 

Chemical properties of acids

1. Neutralization reaction: This a kind of a reaction where an acid reacts with a base to form salt and water.

HCl(aq) + NaOH(aq) ---> NaCl(s) + H2O(l)

HNO3(aq) + NaOH(aq)
---> NaNO3(s) + H2O(l)

 

2. Reaction with Metals: When an acid reacts with metals higher than hydrogen in the activity or electrochemical series, hydrogen gas will be evolved.

Zn(s) + 2HCl(aq) ---> ZnCl2(aq) + H2(g)

2Al(s) + 6HCl(aq) ---> 2AlCl3(aq) + 3H2(g)

 

3. Reaction with carbonates: When an acids reacts with carbonates, salt and water is produced as carbon(IV)oxide is given off.

Na2CO3(s) + H2SO4(aq) ---> Na2SO4(s) + H2O(l) + CO2(g)

CaCO3(s) + H2SO4(aq) ---> CaSO4(s) + H2O(l) + CO2(g)

 

4. Reaction with bicarbonates: It is similar to the reaction with carbonates in the sense that salt, water and carbon(IV)oxide is produced.

KHCO3(s) + HCl(aq) ---> KCl(aq) + H2O(l) + CO2(g)
 
NaHCO3(s) + HCl(aq) ---> NaCl(aq) + H2O(l) + CO2(g) + H2O(l)


Amazing facts in Chemistry

Gold and copper are the only two non-silvery colored metals. Please read some interesting facts about gold here

Copper is the only metal that is naturally antibacterial. This is why you would see some children carry copper water bottles to school

Water actually freezes faster when it’s warm than when it’s cold

Most element in their pure state exists physically in different forms. For instance, pure carbon can exist as both diamond and graphite. This phenomenon is called allotropy.
Please read on modification of Dalton's atomic theory here.

If you pour a handful of salt into a full glass of water, the water level will go down rather than overflowing the glass.

Similarly, if you mix half liter of water and half litre of alcohol, the total volume of the liquid will be les than one litre


NOTABLE POINTS IN Chemistry

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