Record of your data in the table provided below, obnain all weighrr all wapensur
ID: 483880 • Letter: R
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Record of your data in the table provided below, obnain all weighrr all wapensure before weir must be cooled to room Procedure UNKNOWN NUMBER then weigh into it an approximane Wigh a dry porcelain evaporating disb and might weigh For example, your sample have to be exactly 400 3.86 g or Mass of unknown plus evaporating dish Mass of the unknown sample Then slowly add about mL portions of 3 M acid until all of sample and no more bubbles of carbon dioxide are being formed. Do Nor the contents of dish; to of the You can stir rod must not be taken out of the mixture without ng it with a few insi hydrochloric acid. To complete the reaction of your carbonate sample will ndlops of 25 mL of the 3 M HCI. You can check to see that you have an excess of acid by stirring the reaction mixture and the stirring rod on a strip of blue litmus paper: will change color to "red" (pink) if the is acidic. Do NOT dip litmus paper into the reaction mixture. Weigh a watch glass preferably the ribbed type) that will be used to cover the evaporating dih Mass of the watch glass to be used Place the covered dish on a ho plate, and heat it so that the contents boil gently. Because you wm avoid loss of product, try to keep the spattering minimum keeping the glass in placeand controlling the rate of heating. Keepthe watch glass on the evaporating dish throughout the weighing the second time also) because some Naci probably will have spattered up onto iu When the residue in the dish appears to be completely dry, use crucible tongs to remove the and watch glass from the hot plate and set them on an iron ring attached to a ring stand. After the covered dish cools to room temperature, determine the weight of the dish, watch glass, and residul NaCl. Subtract the combined weight of the empty evaporating dish and watch glass to get the weight of the NaCl produced. To make sure that all water has been evaporated, reheat the dib and then recool and reweigh it. Mass of Nacl plus evaporating dish & watch glass after initial hearing Mass of Nac plus evaporating dish & watch glass after second heating Combined mass otevaporating dish & watch slass Mass of the NaCI obtained Now use the unknown and Nach weights to calculate their mole ratio eport section). (see Discard the NaCl residues by washing them into a sink drain. Stoichiometry: Mole Relationshuns.Explanation / Answer
1. the unknown carbonate salt is NaHCO3 as the ratio of NaCl to unknown is 1.
2. Balanced equation,
NaHCO3 + HCl ---> NaCl + H2CO3
3. the possible experimental errors that might occur in this case would be, say If the initial unknown weight was incorrectly measured. The weigh of unknown transferred in the evaproating dishwash incorrectly measured.
4. the product H2CO3 may undergo decomposition to H2O and CO2. Also NaCl may absorb moisture and the weight of final product may increase.
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