Prelab questions- Chemical equations . Can someone help me with this. Pre-Lab Ex

Question

Prelab questions- Chemical equations . Can someone help me with this.

Pre-Lab Exercise: In writing total ionic equations, only certain substances, such as NaCl (aq), are to be converted into separate ions, Na+ (aq) + Cl– (aq). The rule is very simple. A formula is converted into cations and anions IF AND ONLY IF: 1) Substance has the physical state (aq) and 2) it is either an ionic compound or a strong acid. There are 7 common strong acids that you should commit to memory: HNO3 H2SO4 HClO4 HClO3 HCl HBr HI You can assume all other acids are weak acids. ____________________________________________________________________ You should be able to answer the following questions: 1. For each of the following substances, complete the equations to show whether it should be converted into separate ions. The first two have been done for you as examples: 1. Na2SO4(aq) 2Na+ (aq) + SO4 2 (aq) 2. CO2(g) CO2(g) (CO2 does not form ions.) 3. K3PO4(aq) 4. 3Mg(NO3)2(aq) 5. HBr(aq) 6. NaHCO3(aq) 7. CH3OH(aq) 8. MgCl2(s) 9. H2O(l) 10. 2NH4Cl(aq) 2. What precautions must be taken when handling 0.3 M HCl and 0.3 M KOH solutions in the laboratory? 3. What is the function of the phenolphthalein indicator? 4. When an aqueous solution of lead(II) nitrate is mixed with an aqueous solution of sodium iodide a yellow precipitate forms. Use the data in the solubility table to write the (1) molecular, (2) total ionic and (3) net ionic equations for this chemical reaction.

Explanation / Answer

3. K3PO4 ionizes as

K3PO4 --------------> 3K+(aq) + PO4(3-)(aq)

4. Mg(NO3)2 ---> Mg+2 +2NO3-

5. HBr----> H+ +Br-

6. NaHCO3---> Na+ + HCO3-

7.CH3OH

8. MgCl2---> Mg+2 +2Cl-

9. H2O(l)---> H+ +OH-

10. NH4Cl--->NH4++Cl-

2. Since both are corrosive, Wearong safety google is necessary. Wearing the apron is also a must

3.It is an indicator which changes from clear to pink at basic pH of 8.2

4. Pb(NO3)2(aq) + 2NaI(aq) --> 2NaNO3(aq) + PbI2(s) molecular

Pb+2 + 2NO3- + 2Na+ + 2I- ----> 2Na+ + 2NO3- + PbI2 ionic

Pb+2 +2I- ----> PbI2 ionic

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