Competition - post a photo you've taken of nature >>

Calcium + Hydrochloric Acid?

The student had added the exact amount of calcium required to react with the hydrochloric acid used. After carrying out the experiment the student accidentally added more calcium. The student was suprised that the extra calcium still reacted. Explain this observation. Include an equation in your answer.

Ca(s) + HCl(aq) -> CaCl2(aq) + H2(g)

I put that equation down, but I'm not sure why the excess calcium still reacted with the hydrochloric acid? Could somebody help? I'd really appreciate it!

Also,
Br2 + NaCl -> No reaction
Br2 + NaI -> NaBr2 + I

Are those correct? and if so, would the ionic equation (for Br2 + NaI -> NaBr2 + I) be

2Br- + Na+ -> NaBr2 ?

Then, once this has been added to cyclohexane would the hexane layer color be orange? (due to the presence of Bromine ions?) I wasn't sure if the Iodine product would make the hexane layer purple or if the NaBr2 would case it to be Orange.

(edited 10 years ago)

Reply 1

OHNOGEM

The extra calcium could have reacted with the products instead of the HCL?

Reply 2

Eskyy

Original post by OHNOGEM

The extra calcium could have reacted with the products instead of the HCL?

So would the calcium react with the hydrogen? Forming Calcium Hydride (CaH2)?

Reply 3

OHNOGEM

Original post by Eskyy

So would the calcium react with the hydrogen? Forming Calcium Hydride (CaH2)?

Yeah that's what I'm guessing

Reply 4

Mr Chang

The HCL is aqueous, meaning there is water. Therefore the calcium reacted with the water of the solution.

Ca+ 2h2o >>> ca(oh)2 + h2

the excess ca reacts instantly with h20 to form ca2+ and oh- ions

Ca(s) + 2H2O → Ca^2+(aq) + 2OH^-(aq) + H2(g) (ionic form of the reaction)

cah2 would be a very unlikely product in these circumstances

(edited 10 years ago)

Reply 5

Eskyy

Original post by Mr Chang

Okay thank you! I've got that down, now it's just the final question on the paper-

Bromine water is added to aqueous solutions of Sodium chloride and sodium iodide in separate test-tubes. Then an organic solvent, cyclohexane, is added. The test tubes are then shaken.

State what color you would see in the cyclohexane after each test tube has been shaken

Write ionic equations for any chemical reactions that take place

State and explain the trend in reactivity shown by these observations.

so for the chemical equations of the two reactions would be

Br₂+ NaCl -> No Reaction since Br₂can only oxidise Iodine (due to reactivity)

Br₂+ 2NaI -> 2NaBr + I₂Ionic Equation- 2I^-+ Br_2(s)-> 2Br- + I₂
Then adding the first reaction to cyclohexane will give an orange colour, in the hexane layer (due to Br₂ present)? Where the 2nd reaction will give a purple color, in the hexane layer (due to I₂present)?

Then this shows the reactivity as Bromine is less reactive than Chlorine, shown by no reaction happening in the first instance, and then shows that Bromine is more reactive than Iodine and hence a reaction occurs?

(edited 10 years ago)

Reply 6

charco

Study Forum Helper

Original post by Eskyy

yup, you have it all ...

Reply 7

Dustekhub

HCl is diluted, it means that still there is water in the solution. Ca reacts with rest water.Br is less reactive than Cl. Cl in halogen group can be displaced by fluorine but not Br an I

Reply 8

Lday56

this does not help at all we need a straight answer no blabbering please think before you type. now can someone answer my question of What would happen if Calcium was added to Hydrocloric acid??