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Chem Questions. David added some dilute hydrochloric acid to some solid limestone...

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user707 | eNoter

Posted January 15, 2013 at 10:34 AM via web

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Chem Questions. 

  1. David added some dilute hydrochloric acid to some solid limestone (calcium carbonate) in a beaker. When he weighed the products after the bubbling had stopped, he noticed that there had been a reduction in mass. Explain why his result did not seem to agree with the Law of Conservation of Mass.
  2. Jessica heated some bright blue copper(II) nitrate crystals in a test tube. She noticed brown nitrogen dioxide gas being produced. A glowing splint held at the top of the test tube re- lit, proving that oxygen gas was also produced. A fine black solid, copper(II) oxide, was left in the test tube. 
    1. In this reaction state the reactants and the products
    2. Construct the word equation for this reaction

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jerichorayel | College Teacher | (Level 1) Senior Educator

Posted January 15, 2013 at 12:45 PM (Answer #1)

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1. The reaction of Calcium Carbonate and hydrochloric acid will produce Calcium chloride, water and CO2 in the form of gas (bubbling). Now the Mass should have to be heavier because Calcium chloride is produced.

Balanced chemical equation

CaCO3 (s) + 2HCl (aq) --> CaCl2(aq) + H2O (l) + CO2 (gas)

Reactants: CaCO3 + HCl

Products: CaCl2 + H2O + CO2

2. Balanced chemical equation

2Cu(NO3)2 (s) -> 2CuO (s) + 4NO2 (gas) + O2 (gas)

Reactants: Cu(NO3)2

Products: CuO + NO2 + O2

The thermal decomposition of Copper (II) Nitrate will produce Copper (II) oxide, Nitrogen dioxide gas and oxygen gas.

 

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