Chemical changes:
- permanent
- new substances formed
- permanent
- new substances formed
- irreversable
- involves chemical change
- heat/light energy may be taken in or given out
- heat/light energy may be taken in or given out
- properties of starting reactants differ from products
- for example, cooking, burning of charcoal and steel rusting
- for example, cooking, burning of charcoal and steel rusting
Physical change:
- temporary
- no new substances formed
- reversable
- no new substances formed
- reversable
- does not involve chemical change
- no/little light or heat energy is given in or taken out
- properties of substances do not change
- for example, changes in state and dissolving salt
Chemical reactions:
- changing reactants into products
- provides identies of reactants and products
- provides possible reaction possibilities
- represented using chemical equations
- for example, changes in state and dissolving salt
Chemical reactions:
- changing reactants into products
- provides identies of reactants and products
- provides possible reaction possibilities
- represented using chemical equations
- can be written using word or chemical equation
Balanced chemical equation:
2) check atoms of each elements on both sides of the reaction
3) balance the chemical equation by placing numbers in front of the element in the question
- for example, N3+H2=NH3
N2+3H2=2NH3
N2+3H2=2NH3
Chemical equations involving heat
- combustion
- combination
- thermal decomposition
Combustion:
- burning
- substance combine with oxygen in the air
- products are heat and light
- products are heat and light
- octane+oxygen+heat=carbon dioxide+water
Combnation:
- two or more reactants combine chemically to form a new product
- two or more reactants combine chemically to form a new product
- sodium+chlorine=sodium chloride
Thermal decompositon:
- a substance breaks down into two or more simpler substances(decomposition)
- a substance breaks down by the effect of heat(thermal decomposition
- a substance breaks down by the effect of heat(thermal decomposition
-sugar+heat=carbon+water vapour
chemical reactions involving light:
- photosynthesis
- photography
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjN_FciK3ceGqRsADf9yX-B3H_hRLtxDoA3WhNpgdNmz8y6sWxy4pxjNHsGVA_Qcu8q0Cl12901PAxER_Oe6XKIpIcoHg-uxb63w6HDzmX_0qBOtJIlMRJ64Jomgk9SSEhbXbxRs4NqXvb/s320/photosynthesis.jpg)
Photosynthesis:
- green plants in the presence of chlorophyll and light energy manufacture carbohydrates(glucose) from carbon dioxide and water
- carbon dioxide+water+light energy+chlorophyll=glucose+water
Photography:
- when films are exposed to light, silver bromide decomposes to form silver particles
- silver bromide+light energy=silver+bromine
Electrolysis;
Electrolysis;
- passing electric currents may change the propeties of the substance temporarily or permanently
- some substances decomposes into simpler ones when electricity is passed through![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhz6ZeHr9cIt85lyhftodMrc1fo9uM-V8IDsHhecL7IgzPqHh5mteXjyBsKtX_uCXcdeI8_L-akfYziWsErg6x6qRT1yAdMHc8qMbZx_y6ma8K44EFX6_s7E_CC4Wzb_2U1tuBqGGvmB1Z6/s320/electrolysis.jpg)
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhz6ZeHr9cIt85lyhftodMrc1fo9uM-V8IDsHhecL7IgzPqHh5mteXjyBsKtX_uCXcdeI8_L-akfYziWsErg6x6qRT1yAdMHc8qMbZx_y6ma8K44EFX6_s7E_CC4Wzb_2U1tuBqGGvmB1Z6/s320/electrolysis.jpg)
- electroplatimg
Chemical reactions involving matter:
- digestion
- digestion
- neutralisation
- rusting
- rusting
Digestion:
- involves chemical reactions caused by mixing
Neutralisation
- hydrochloric acid+sodium hydroxide=sodium chloride+water
Rusting
- iron comes in contact with oxygen in the air and water
- iron comes in contact with oxygen in the air and water
- combination
- iron+oxygen+water=hydrated iron(III)oxide
your photo for NaCl is incorrect- the equation is not properly balanced- it should be
ReplyDelete2Na + Cl2 -> 2NaCl
:)