Chemical Change vs. Physical Change: Can YOU Spot the Difference?

We began learning about chemical and physical changes in class. We learnt that a chemical change occurs when when a new substance is made, & old bonds are broken while new ones are made. An example of a chemical change would be cooking an egg On the contrary, physical changes DO NOT produce a new substance. An example would be ice melting --> the ice melts into water however the same substance is present, there's just a change in state.





The diagram below shows the changes in state when they undergo any physical changes :

In order to spot the difference between the two, we took many things into consideration:

• colour change
• change in state
• odour
• light
• heat

Another simple way to tell if a chemical or physical change has occurred is by looking at its chemical equation. Let's say, for example, an ice cube melted and I was trying to detect which change it had gone through, but I was still unsure even after I did an expirament. I would look at it's chemical equation:

Ex. H₂O (s)à H₂O (l)

I noticed that the reactant was the same as the product, the only difference is the change in state from a solid (s) to a liguid (l).

Naming Acids

Naming Simple Acids

Acids that have only 2 components are called binary acids.  Usually they contain hydrogen and another element.  E.g. HF- hydrofluoric acid. 

To name them, put the prefix 'hydro' infront of the anion and change the the ending to 'ic'. 

E.g. -HCl -> hydro + (choride = chloric) + acid -> hydrochloric acid

       -HBr -> hydro + (bromide = bromic) + acid -> hydrobromic acid

       -HCN -> hydro + (cyanide = cyanic) + acid -> hydrocyanic acid

Naming Complex Acids

Complex acids are acids which have hydrogen and a polyatomic anion. 

To name them, first find the anion.  If the anion ends in 'ate', change the ending to 'ic', but if the anion ends in 'ite', change the ending to 'ous'.  Add 'acid' to the end.

E.g. -HClO₄   -> (perchlorate = perchloric) + acid -> perchloric acid

       -H₃PO₄  -> (phosphate = phosphic) + acid -> phosphic acid

       -HNO₂   -> (nitrite = nitrous) + acid -> nitrous acid

For more information, visit:

http://www.sciencegeek.net/Chemistry/chempdfs/NamingAcids.pdf

MATTER !!!

Matter is a substance that has MASS and takes up VOLUME.  Matter has 3 states: solid, liquid, gas.

There are two types of matter: pure substances and  mixtures. 



Pure substances:

- fixed composition
- contains atoms of only 1 kind
-fixed physical and chemical properties
-fixed ratios of elements


Pure substances are divided into two more subgroups: elements and compounds

Elements:

-cannot be broken down to further substances
- examples: Helium, Carbon, and Aragon.
-made out of atoms: metals, metalloids, non-metals


Compounds:

-formed by two or more elements.
-example: water  (2 hydrogen + 1 oxygen)
-examples: Methane, carbon dioxide, and sodium chloride.
-can be either covalent (organic compound) or ionic (acid, salt, base).


Mixtures:

-contain at least two substances
- not chemically combined
-can be separated into pure compounds or elements
-has a changing set of physical properties


There are two types of mixtures:  Homogeneous and Heterogeneous.

Homogeneous:

-"homo" --> same
-has uniform  properties and compositions throughout.
-commonly referred to as solutions
-example: table salt mixed in water

Table salt mixed into water creates a homogeneous mixture. One is unable to see the different substances when mixed together.

*it can be either a solution or a colloid*

Heterogeneous:

-"hetero" --> difference
-containing two or more substances, but not "mixed".
-contains different visible substances seen with the naked eye.
-example: cake mix and cookie dough

                dried beans, rice, and vegetables mixed together is an example of a heterogeneous mixture

*heterogeneous can be either suspension or mechanical mixture.*

DIAGRAM OF MATTER

Chemical and Physical Changes

Solids
-have a set mass and volume
-particles are arranged in regular patterns
-particles can only vibrate in place

Liquids
-take the shape of their container
-enough room between particles to slide past one another

Gases
-move freely
-undefined mass and volume