Exercise A Calculating the molar mass of a compound (2 pts...

Exercise A Calculating the molar mass of a compound (2 pts per answer) Using the periodic table at the end of this worksheet, calculate the molar mass of the following compounds. Then calculate the number of moles in 140 grams of the compound Fe2(SO4)3: molar mass = __________ Number of moles in 120. grams __________ NI3: molar mass = __________ Number of moles in 120. grams __________ Sr(CO3)2: molar mass = __________ Number of moles in 120. grams __________ Exercise B - Balance the following chemical equations (3 points per equation) Balance the following chemical equations: Ca3(PO4)2 + SiO2 + C ? P4 + CaSiO3 + CO NaHCO3 ? Na2CO3 + CO2 + H2O C5H12 + O2 ? CO2 + H2O KMnO4 + HCl ? MnCl2 + KCl + Cl2 + H2O (Cl is chlorine in this equation) Ca(ClO)2 + HCl ? CaCl2 + H2O + Cl2 (Cl is chlorine in this equation) Cu + HNO3 ? Cu(NO3) + NO2 + H2O

Transcript

00:02 Hello everyone, let's look at the question.

00:04 So here we are given to certain compounds and we have to find out the molar mass as well as number of moles of that compound for the given mass of the compound.

00:18 Okay.

00:18 Now here, so the first let us take the first compound.

00:21 So here the first compound is fe2 so4 thrice.

00:27 Fe to so4 thrice.

00:32 Now to find out the molar mass, what we should do is we should add.

00:36 The atomic mass of every atom present in the molecule.

00:39 Now here first let me take fe.

00:41 Fe is having so 56 atomic weight so since two atoms are they you should multiply this by 2.

00:49 Okay now plus so sulfur is 32 for sulfur it's 32 and for oxygen 16 multiplied by 4 so whole multiplied by 3.

01:02 Okay now if you do that so the answer is so 400 gram per mole so the molar mass of this compound is 400 gram per mole now if you want to calculate number of moles so here it is asked to find out number of moles are presenting 120 gram of this compound so number of moles can be calculated by mass divided by molar mass so here it is mass is 120 gram and here molar mass is 400 now if you do that so here the answer is 0 .3 mole okay so this is for first compound now the second compound is n i 3 now for this the molar mass is now so for nitrogen it is 14 plus for iodine it is 127 so 127 multiplied by 3 now if you calculate that so it is equal to 395 gram per more okay now let us calculate the number of moles present in 120 gram of this compound.

02:18 So number of moles is equal to mass divided by molar mass.

02:29 So this is equal to 120 divided by 395.

02:33 So this is equal to 0 .303 mole.

02:38 Okay.

02:39 Now let us move on to the third compound.

02:42 So the third compound is, so the third compound is, so the third compound is strontium carbon carbonate co3 twice so here the molar mass is so for strontium it is 88 88 plus 12 plus 16 multiplied by 3 whole multiplied by 2 if we do that so the answer for this is 208 gram per mole so here again if you calculate the number of moles present in 120 gram mass by molar mass so this is equal to 120 divided by so 208 gram per mode so this is equal to 0 .577 mole okay so this is for one set of questions now if we take second set we have to balance the given chemical equations now so the first equation is ca 3 p o4 twice p o four twice plus sio2 2 plus carbon giving p 4 plus c -a -s -i -3 plus co okay now we should balance this so here we can see that calcium here it is 3 okay now here it is only one calcium is there okay now if i take the phosphorus so here it is posperous is 2 okay now here here it is 4...

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