1) When we say calcium reacts readily with cold water, it means the reaction is moderately fast?
2) When we react Fe with dilute HCl, we get FeCl2 & H2. Why won't we get FeCl3?
3) Similarly, when we react Fe with CuSO4, displacement reaction occur to give FeSO4 & Cu. Why won't we get
Fe2(SO4)3?
http://books.google.com/books?id=STxHXRR4VKIC&pg=PA312&lpg=PA312&dq=iron+oxidation+states+stability+energy&source=web&ots=EE_tKI93-T&sig=cEGksSOaiTNI9CogX7QRzRvHE0o&hl=en&ei=7t6ESaeiIImIsAPpm-29DQ&sa=X&oi=book_result&resnum=4&ct=result#PPA333,M1
see page 333 to answer the third question. The point on that page is that FeII ion is stable, even in water, and the FeIII is relatively stable. IT is a matter of free energy.
On the first question above, Yes, it is moderately fast.
1) When we say calcium reacts readily with cold water, it means the reaction is indeed fast. In order to determine the rate of a chemical reaction, we typically consider the speed at which the reactants are consumed or the products are formed. In this case, calcium reacts moderately fast with cold water, meaning it undergoes a chemical reaction at a relatively high rate.
To experimentally verify the reaction rate, you can conduct a simple experiment. Take a small piece of calcium metal and carefully add it to a container of cold water. Observe the reaction and note how quickly the calcium reacts with the water. The rapid appearance of gas bubbles and the formation of a white precipitate (calcium hydroxide) will indicate a moderately fast reaction.
2) The reason we don't get FeCl3 when we react iron (Fe) with dilute hydrochloric acid (HCl) is because iron(III) chloride (FeCl3) is not stable in dilute HCl solution. Instead, the reaction between Fe and dilute HCl forms iron(II) chloride (FeCl2) and hydrogen gas (H2).
To understand why FeCl3 is not produced, you can consider the oxidation states of iron in FeCl2 and FeCl3. In FeCl2, iron has an oxidation state of +2, while in FeCl3, iron has an oxidation state of +3. Dilute HCl contains chloride ions (Cl-) that can react with Fe(III) to form FeCl3. However, the presence of excess HCl prevents the formation of FeCl3 by keeping the iron in the +2 oxidation state. This is because the reaction between Fe(III) and HCl produces FeCl2, which stays dissolved and prevents further oxidation of iron to Fe(III) state.
3) When iron (Fe) reacts with copper sulfate (CuSO4) in a displacement reaction, FeSO4 and copper (Cu) are formed. The reason we don't get Fe2(SO4)3 (iron(III) sulfate) is due to the relative reactivity of iron and copper.
In displacement reactions, a more reactive metal can displace a less reactive metal from its compound. In this case, iron (Fe) is more reactive than copper (Cu). When Fe reacts with CuSO4, the iron atoms displace the copper atoms in the compound, resulting in the formation of FeSO4 (iron(II) sulfate) and copper (Cu).
Fe2(SO4)3 contains iron(III) ions, which are more stable in solutions with a high concentration of sulfuric acid (H2SO4). In the given reaction, where Fe reacts with CuSO4, the concentration of sulfuric acid is low, as it is part of CuSO4. Therefore, Fe2(SO4)3 is not formed in this reaction.
To further understand this, you can compare the reactivity series of metals. Iron is higher in the reactivity series than copper, indicating that it can displace copper from its compounds.