alevel chem question

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sarahjanesmith
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#1
can someone work these out + expalim it to me please i have no clue what to do

4(a). Hydrated copper(II) methanoate, Cu(HCOO)2•xH2O, is a copper salt.

A student carries out the procedure below to prepare Cu(HCOO)2•xH2O and to determine the value of x in its formula.

Step 1
The student prepares Cu(HCOO)2•xH2O by reacting a copper compound with aqueous methanoic acid to form Cu(HCOO)2(aq) and allowing the solvent to evaporate.

Step 2
The student dissolves 2.226 g of Cu(HCOO)2•xH2O in water and makes up the solution to 250.0 cm3.

Step 3
Using a pipette, the student adds 25.0 cm3 of this solution to a conical flask followed by an excess of KI(aq).
The Cu2+(aq) ions react to form a precipitate of copper(I) iodide and I2(aq).
In this reaction, 2 mol Cu2+ form 1 mol I2.

Step 4
The student titrates the iodine in the resulting mixture with 0.0420 mol dm−3 Na2S2O3 (aq).

I2(aq) + 2S2O32−(aq) → 2I−(aq) + S4O62−(aq)

23.5 cm3 0.0420 mol dm−3 Na2S2O3 (aq) is required to reach the end point.
Complete the electron configuration of copper in



(b). Choose a suitable copper compound for step 1, and write the full equation for the reaction that would take place to form Cu(HCOO)2(aq).

State symbols are not required.
[1]

(c). Write an ionic equation, including state symbols, for the reaction in step 3.





(e). Determine the value of x in Cu(HCOO)2•xH2O.

Show your working.
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Davies Chemistry
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#2
(Original post by dingding123)
can someone work these out + expalim it to me please i have no clue what to do

4(a). Hydrated copper(II) methanoate, Cu(HCOO)2•xH2O, is a copper salt.

A student carries out the procedure below to prepare Cu(HCOO)2•xH2O and to determine the value of x in its formula.

Step 1
The student prepares Cu(HCOO)2•xH2O by reacting a copper compound with aqueous methanoic acid to form Cu(HCOO)2(aq) and allowing the solvent to evaporate.

Step 2
The student dissolves 2.226 g of Cu(HCOO)2•xH2O in water and makes up the solution to 250.0 cm3.

Step 3
Using a pipette, the student adds 25.0 cm3 of this solution to a conical flask followed by an excess of KI(aq).
The Cu2+(aq) ions react to form a precipitate of copper(I) iodide and I2(aq).
In this reaction, 2 mol Cu2+ form 1 mol I2.

Step 4
The student titrates the iodine in the resulting mixture with 0.0420 mol dm−3 Na2S2O3 (aq).

I2(aq) + 2S2O32−(aq) → 2I−(aq) + S4O62−(aq)

23.5 cm3 0.0420 mol dm−3 Na2S2O3 (aq) is required to reach the end point.
Complete the electron configuration of copper in



(b). Choose a suitable copper compound for step 1, and write the full equation for the reaction that would take place to form Cu(HCOO)2(aq).

State symbols are not required.
[1]

(c). Write an ionic equation, including state symbols, for the reaction in step 3.





(e). Determine the value of x in Cu(HCOO)2•xH2O.

Show your working.
Hi,

here are a few tips to get you started...please see attachment
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Davies Chemistry
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#3
(Original post by Davies Chemistry)
Hi,

here are a few tips to get you started...please see attachment
and here is a bit more detail.. see attachment
Attached files
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sarahjanesmith
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#4
Report Thread starter 11 months ago
#4
(Original post by Davies Chemistry)
and here is a bit more detail.. see attachment
thank you so much for this. i will checkout the channel too. it makes sense now
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