Grade 9 Chem Help????

Ok, so yesterday in class we had to an experiment and determine if a physical or a chemical change had occurred. I missed part of class, and do not understand at all!

Can you help me? Would the following be a chemical or physical change? And please say why? Thanks in advance.

a) Water mixed with Copper Sulfate

b)Iron Nail added into the water/copper sulfate solution

c) Hydrochloric acid added into the water/copper sulfate solution

d)Magnesium and water mixed together.

Thanks Again!

Comments

  • a) This is a physical change, because when you mix two substances, they can be separated. The water could be evaporated to isolate the copper sulfate.

    b) This is also a physical change, for the same reasons mentioned above. The nail could be physically removed from the water.

    c)This is a chemical change, because the HCl obviously reacted with the copper sulfate in the solution. If you observed any color changes, production of a heat or gas (bubbling), or an odor, this is ALWAYS evidence of a chemical reaction.

    d)This is a physical change, because magnesium will not react when added to water. However, if you were to mix magnesium oxide with water, a reaction WOULD occur - producing magnesium hydroxide.

    Hope that helps.

  • a chemical change is a change that occurs and changes the identity. a physical change is a change that occurs and only changes shape or look, but the object doesnt change identity. so if i burned a piece of paper, its a chem. change b/c its no longer paper, its ashes. if i hit a piece of metal with a hammer and make it flat, its still metal, but its just flat. thats a physical change. so:

    a= physical

    b= physical

    c= chemical

    d= physical

    its all about identity. good luck kid :)

  • definite Be is very solid(extra solid than the two Li and B that are on the two part of it) yet understand this, valency implies to the variety of electrons donated/gained/shared in bonding and Be types 2 bonds( case in point BeCl2, that's molecule with an incomplete octate) so its valency is two. even the Noble gases with solid configurations (case in point Xe) types bonds and characteristic a valency so why not Be?? i comprehend this isnt precisely a scientific rationalization yet desire i became atleast being in part powerful:)

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