Homework Help Forum: Chemistry

Posted by Alex on Friday, June 5, 2009 at 2:40am.

4.How many grams of calcium chloride can be prepared if a student uses 500g if calcium carbonate and 2.00L of a 4.00 Mol/L sodium chloride solution in the reaction.?? 5. 2KMnoO4 + 5 H2C2O4<----need to use this Concentration of 0.24L KMnO4 solution required to oxidize 2.7g of Oxalic Acid??? 6.What volume of 0.100mol/L aqueous sodium hydroxide(NaOH) is neutralized by 500ml of 0.200mol/L hydrochloric acid(HCI) ?? 7.When 10.0g of potassium chlorate,KCIO3,decomposes,what volume of oxygen is obtained(at 18C and 750 mm HG pressure) ??

• Chemistry - MathMate, Friday, June 5, 2009 at 8:25am

  4.How many grams of calcium chloride can be prepared if a student uses 500g if calcium carbonate and 2.00L of a 4.00 Mol/L sodium chloride solution in the reaction.?? Alex, could you check the question? Calcium carbonate does not react directly with sodium chloride to make calcium chloride, just like sea water does not dissolve lime-stone. Otherwise many parts of the world would be eroded by the sea. However, it is easily possible to make calcium chloride from hydrochloric acid through the reaction: CaCO3 + 2HCl -> CaCl2 + H2O

  
  

• Chemistry - MathMate, Friday, June 5, 2009 at 8:50am

  5. 2KMnoO4 + 5 H2C2O4<----need to use this Concentration of 0.24L KMnO4 solution required to oxidize 2.7g of Oxalic Acid??? This is a complex redox reaction in which the potassium permanganate oxidizes the oxalic acid in an acidic solution (presence of H+ ions. The net reaction is shown below, where the H+ ions would normally supplied by sulphuric acid or another strong acid. 5H2C2O4 (aq) + 6H+ + 2MnO4- (aq) --> 10CO2 (g) + 2 Mn2+(aq) +8H20 (l) This is a very interesting titration where there is an effect of autocatalysis and no indicator is required because of the colour of potassium permanganate. Read up the following articles for your interest and information: http://jchemed.chem.wisc.edu/JCeSoft/CCA/CCA3/MAIN/AUTOCAT/PAGE1.HTM http://www.peerpapers.com/essays/Determination-Molarity-Permanganate-Solution-Via-Titration/40919.html?read_essay By using the ratio of molecular weights of 2KMnoO4 + 5 H2C2O4, you should have no problem calculating the molarity of KMNO4 required. Refer to solution for questions 1-3 for how this can be done. (ref:http://www.jiskha.com/display.cgi?id=1244169404)

  
  

• Chemistry - MathMate, Friday, June 5, 2009 at 8:55am

  6.What volume of 0.100mol/L aqueous sodium hydroxide(NaOH) is neutralized by 500ml of 0.200mol/L hydrochloric acid(HCI) ?? NaOH + HCl --> NaCl + H2O From 500 ml of 0.2 mol/l of HCl contains (500/1000)*0.2=0.1 mole of HCl, and 1 litre of 0.1 mol/l of NaOH contains 0.1 mole of NaOH, we conclude that 1 litre of 0.1 mol/l NaOH aqueous solution is required.

  
  

• Chemistry - MathMate, Friday, June 5, 2009 at 9:03am

  7.When 10.0g of potassium chlorate,KCIO3,decomposes,what volume of oxygen is obtained(at 18C and 750 mm HG pressure) ?? 2KClO3 + heat -> 2KCl + 3O2 Managanese dioxide is used as a catalyst for this reaction. Molecular weight of KClO3 =39+35.5+3*16=122.5 Number of moles of oxygen produced =10/(2*122.5)*3 =0.1224 mole Volume of oxygen = 0.1224*22.4 l. = 2.74 litres

  
  

• Chemistry - MathMate, Friday, June 5, 2009 at 9:03am

  Erratum: Manganese dioxide

  
  

• Chemistry - Alex, Friday, June 5, 2009 at 2:03pm

  yes..for #4 it is hydrochloric acid i forgot to put it in,how would u find the grams of calcium chloride???Thank you MathMate

  
  

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