Why 1 is C? The compound Na2CO3.10H2O…. Na has 2 atoms so (2x23) C has 1 atom so(12), O has 3 atoms so ( 3x16), H has 20 atoms so ( 10x2) then O again has 10 atoms so ( 10x16)
Why 2 is D?As you see.. one mole of chlorine atom has a mass of 35.5g …And chlorine molecules formula is Cl2 so.. the mass of one mole chlorine molecule is 71g… So the answer is just straight forward… asking for the number of molecules in one mole of chlorine molecule… 6x 1023
Why 3 is B? Hmm this one is quite diff to explain.. LOL...Nvm.. read the chem txtbk you will understand
Why 4 is D? Try to work it out... hahah... Follow the example in pg141 of your txtbk.. Sure can get
Why 5 is D?As you can see.. XCl is an ionic compound… The Ar of X can be obtained by just substracting the Mr of XCl with the Ar of Cl…( 74.5 – 35.5).. The question asking abt oxide of X.. so As X has a positive charge.. and oxide has 2 negative charge… The chemical formula for the compound is X2O.. Thus.. the Mr of the compound is (2 x Ar of X) + ( 16)
Ok... now is qns 6... haha... Firstly you need to find the number of mol of the gas.. to find it just divide the volume of gas with the molar volume of the gas in r.t.p..( read the txtbk if you dont understand this).. The next step is by dividing the mass of the gass with the mol you obtained in the previous step.. After you get it the Ar of the gas you got is the same as oxygen… and the Qns is asking abt the Mr of the gas which is gas2 the same as o2 haha… thus you can get the Mr ( 2 x 16)
Qns 7 now... hahah...First part...You need to find the Mr of TiCl3 first…( 48) + ( 3x 35.5)= 154.5…. Then find the number of moles that TiCl3 have by dividing the mass of the compound with the Mr of the compound… ( 38.6/154.5). you get 0.25 mol( correct to 3sf)
Ok now 2nd part... quite complicated..In 1 mol of TiCl3 it contains : 1 mole of Ti atoms and 3 mole of Cl atoms… So.. number of moles of Ti atom has in the compound is ( 1x 0.25). From here you can work out to obtain the mass of Ti..=( amt of mol Ti has)x( molar mass of Ti)
For 7b... hmmm quite straight forward.. Find the number of moles the Cl has in the compound and work it out with the avogrado's constant...
For 8a.. quite easy... read the txtbk page 136.. sure understand..
8b quite tedious...follow the example in pg 138-142 of the txtbk..Sure can..
challenge qns 2
challenge qns 2
qns 1
Qns 2
Qns 3
Qns 4