Science

1.)​CaCO3→CO2​+CaO
A scientist heats 30 grams of calcium carbonate (CaCO3) in the chemical reaction shown. What is the total mass of the products?(1 point)
A.)10 grams
B.)15 grams
C.)60 grams <<<<
D.)30 grams

2.)Fe+O2→Fe2O3​
What happens to atoms of Fe and O2 during the reaction?(1 point)
A.)They are lost.
B.)They are rearranged.<<<<
C.)They maintain their properties.
D.)They gain mass.

3.)What is most likely to occur during a chemical reaction?(1 point)
A.)New atoms are created.
B.)Mass is conserved.<<<<
C.)The original substance maintains its properties.
D.)Molecules of the original substance are lost.

{4.}NaHCO3+HC2H3O2→NaC2H3O2+H2O+CO2
A student mixes baking soda (NaHCO3) and acetic acid (HC2H3O2) to produce a chemical reaction shown. Which statement about the reaction is correct?(1 point)
A.)Atoms of Na are destroyed during the reaction.
B.)Some atoms gain mass after the reaction.
C.)There are more H atoms after the reaction.
D.)The atoms of the reactants are regrouped during the reaction.<<<<

{5.}2H2+O2→2H2O
There are four atoms of hydrogen (H) before the reaction. How many atoms of hydrogen are present after the reaction?
(1 point)
A.)8
B.)2
C.)5
D.)4<<<<

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  1. 1. Nope. You start with 30 g CaCO3. You can't get more total products than you started with.
    2. OK
    3. OK. But why didn't you use this in answering 1.
    4. OK
    5. OK

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    DrBob222
  2. I thought you had to add more since he only heated up 30

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  3. and thank you

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  4. Add more what?
    CaCO3 ==> CaO + CO2
    We can calculate grams CaO and grams CO2 produced from 30 g CaCO3, which I will do, but that isn't needed if you remember that the Law of Conservation of Mass says that matter is not created nor destroyed. So if you start with 20 grams CaCO3 you must end up with a total of 30 grams on the other side. mass CO2 + mass CaO = 30 g. But we can prove that's correct by calculating the mass of each and adding them together.
    mols CaO = grams/molar mass = 30/100 = 0.3 mols CaCO3
    We get 0.3 mol CO2 and 0.3 mol CaO.
    grams CO2 = mols x molar mass = 0.3 x 44 = 13.2 g
    grams CaO = mols x molar mass = 0.3 x 56 = 16.8 g
    g CaO + g CO2 = 16.8 + 13.2 = 30.0
    Voila!

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    DrBob222
  5. oops. I made a typo. If you start with 30 grams CaCO3 you must end up with 30 grams of products. Now I see your reasoning. You're thinking that 30 grams CaCO3 will give you 30 g CO2 and 30 g CaO to make a total of 60 grams but it doesn't work that way. You can see from my calculations how much CO2 and how much CaO are produced. The bottom line is the Law of Conservation of mass. Sorry about the typo. My eye sight isn't that good.

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    DrBob222
  6. As I can see here your saying that it is 'C, A, D, B, D' based on some new rearrangements.

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  7. anonymous is right but 1 is 30 grams not 60

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  8. the last question is 4 not 2 but i’m not very smort and anonymous are right otherwise

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  9. The answers to the Chemical Reactions quiz are:
    1. 30 grams
    2. They are rearranged
    3. Mass is conserved
    4. The Atoms of the reactants are regrouped during the reaction
    5. 4
    Hope I could help:)

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  10. trust me is correct make sure to read the answer they might be wrong

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  11. Trust me is right

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  12. @Trustme is right
    Thank you

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  13. Thx Trustme!!!

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