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[ Relative atomic mass: Relative Atomic Mass FIRST STEP: Mass 1. Calculate the number of atoms in 1.28 g of copper? Find the Cu = 64; NA = 6 x 1023 mol-1 ] Number of MOLES = using 1.28g NEXT mol Relative Molecular Mass [ Relative atomic mass: Mass 2. FIRST STEP: Calculate the number of in 4.4g of vitamin C, C6H8O6 Find the H = 1; C = 12; O = 16; NA = 6 x 1023 mol-1 ] Number of MOLES molecules = using 4.4g NEXT mol use 0.6 g to find the number of moles of NH3 [ Relative atomic mass: Use NA to find the number of atoms of NH3 3. in 0.6g of NH3 gas evolved during an experiment FIRST STEP? What is the Calculate the number of N = 14 ; H = 1; O = 16; NA = 6.02 x 1023 mol-1 ] atoms NEXT Relative Molecular Mass [ Relative atomic mass: Mass 4. FIRST STEP: in 0.6g of NH3 gas evolved during an experiment Calculate the number of use 0.6 g to Find the N = 14 ; H = 1; O = 16; NA = 6.02 x 1023 mol-1 ] atoms Number of MOLES = 0.035 NEXT mol use RMM to find the number of atoms of H2O2 use 10 g to find the number of moles of H2O2 [ Relative atomic mass: What is the first step? is used, find the mass of oxygen released? 5. FIRST STEP: If 10 g of hydrogen peroxide Hydrogen peroxide decomposes as below 2H2O2 H = 1; O = 16; ] 2H2O + O2 NEXT Mass Relative Molecular Mass FIRST STEP: [ Relative atomic mass: is used, find the mass of oxygen released? 6. If 10 g of hydrogen peroxide Hydrogen peroxide decomposes as below use 10g to Find the 2H2O2 H = 1; O = 16; ] 2H2O + O2 Number of MOLES = 0.147 NEXT mol The 2nd STEP mole= mole = mole= 22.4 dm3(STP) No. atom 24dm3 (room t) vol vol NA mole= mole= RAM/RMM/RFM the problems use the correct FORMULA mass No. molecule NA to solve NEXT [ Relative atomic mass: FIRST STEP: SECOND STEP: 8. Calculate the number of atoms in 1.28 g of copper? use 1.28g to Find the USE THE FORMULA Cu = 64; NA = 6 x 1023 mol-1 ] Mole = No of Atoms N Number of MOLES A NEXT [ Relative atomic mass: What is the number of mole =number of atoms x NA number of mole = number of atoms ÷ NA 9. Calculate the number of atoms in 1.28 g of copper? use the formula SECOND STEP ? Cu = 64; NA = 6 x 1023 mol-1 ] NEXT Number of C6H8O6 Molecules= [ Relative atomic mass: SECOND STEP: From the first step, the number of moles of C6H8O6 is Number of MOLES 0.025 mol 10. Calculate the number of in 4.4g of vitamin C, C6H8O6 Use the formula = H = 1; C = 12; O = 16; NA = 6 x 1023 mol-1 ] number of molecules molecules N X 6X1023mol-1 A NEXT First: use 0.6g to find the number of moles of NH3, SECOND: use formula of mole=No. of atoms ÷ NA [ Relative atomic mass: 11. first: Use numbers of atoms x NA , then Second step: find the number of moles of NH3 What is the step of solving this? in 0.6g of NH3 gas evolved during an experiment Calculate the number of N = 14 ; H = 1; O = 16; NA = 6.02 x 1023 mol-1 ] atoms NEXT First: use 3.4g to find the number of moles of NH3, SECOND: use formula of mole=No. of atoms ÷ NA [ Relative atomic mass: first: Use the formula of mole x NA , then Second step: find the number of moles of NH3 12. What is the step of solving this? in 3.4g of NH3 gas evolved during an experiment Calculate the number of N = 14 ; H = 1; NA = 6 x 1023 mol-1 ] atoms NEXT Step 1: Step 2: Now use the [ Relative atomic mass: 13. in 3.4g of NH3 gas evolved during an experiment Calculate the number of No. of NH3 No. of Moles of NH3= ANSWER molecules to find the no. of N = 14 ; H = 1; NA = 6 x 1023 mol-1 ] NA atoms mol-1 = NH3 X mol-1 molecules X 1023 NEXT Step 2: Step 1: Step 3: [ Relative atomic mass: 14. we want to find number of in 1 molecule of NH3 how many atoms in 3.4g of NH3 gas evolved during an experiment No. of NH3 No. of Moles of NH3= Calculate the number of No. of NH3 molecules = ATOMS 3.4 17 0.2 mol-1 N = 14 ; H = 1; NA = 6 x 1023 mol-1 ] = = = 0.2 X Atoms atoms 6 X 1023 mol-1 x 0.2 mol-1 X1023 of NH3 atoms x 6 x1023 NEXT Step 3: Step 2: Step 1: [ Relative atomic mass: 15. of hydrated copper (II) sulphate CuSO4.5H2O Calculate the mass of Relative Formula Mass No. of Moles of CuSO4.5H2O= Mass of CuSO4.5H2O = = mole x RFM = x O = 16 ; H = 1; S = 32; Cu = 64 ] 0.3 g = mol g no need to find g mol NEXT given Step 3: Step 2: Step 1: [ Relative atomic mass: 16. of Sulphur trioxide SO3 Calculate the mass of Relative Formula Mass No. of Moles of SO3= Mass of SO3 = = mole x RFM = x O = 16 ; S = 32 ] 0.5 g = mol g g mol NEXT given Step 2: Step 1: Step 3: [ Relative atomic mass: 17. of Sulphur trioxide SO3 Calculate the number of atoms 1 molecule of SO3 No. of atoms of 1.5 M of SO3 No. of Moles of SO3= O = 16 ; S = 32; NA=6.02 x 1023 ] = = atoms of S, O,O,O x mole x Avogadro in 1.5 x mol mol NEXT given x1023 Step 2: Step 1: Step 3: [ Relative atomic mass: 18. which has 3.01 x 1023 Calculate the mass RFM of CO2 Mass of CO2 No. of Moles of CO2= = = O = 16 ; C = 12; NA=6.02 x 1023 ] molecules of carbon dioxide CO2 = g No of molecules mole x RFM g NA x in STP NEXT mol [ Relative atomic mass: From the equation, 1 mol of Oxygen O2 used 19. when S + O2 → SO2 and the O2 used is 67.2 dm3 at STP? produce Calculate the S + O2 mole of SO2 volume O = 16 ; S = 32; NA=6.02 x 1023 ] → of sulphur dioxide SO2 SO2 NEXT Moles: molar gas volume=22.4 dm3 STP Volume: No. of moles =Vol ÷ 22.4 when S + O2 → SO2 and the O2 used is 67.2 dm3 at STP? 20. Calculate the [ Relative atomic mass: S + O2 1 67.2 volume 1 dm3 → SO2 of sulphur dioxide SO2 1 ? O = 16 ; S = 32; NA=6.02 x 1023 ] = = Volume of SO2 X dm3 NEXT dm3 Step 2: Step 1: Step 3: 21. at STP Calculate the Find the RMM Divide mass of C2H6 by RMM use the mole x molar gas volume=vol [ Relative atomic mass: H = 1 ; C = 12; molar gas volume=22.4 dm3 STP ] volume of 0.75g of ethane gas C2H6 NEXT Step 2: Step 1: Step 3: 22. at STP Calculate the No. of mole of C2H6 Volume of C2H6 RMM of C2H6= [ Relative atomic mass: H = 1 ; C = 12; molar gas volume=22.4 dm3 STP ] volume = = of 0.75g of ethane gas C2H6 dm3 = g dm3 x mol mol NEXT Step 2: Step 1: Step 3: 23. at room temperature Calculate the Get mole=Divide vol of C3H6 by Molar gas vol use the mole x RMM =mass Find the RMM mass H = 1 ; C = 12; molar gas volume=24 dm3 R.T. ] of 6.72 dm3 of propene gas C3H6 [ Relative atomic mass: NEXT Step 2: Step 1: Step 3: 24. at room temperature Calculate the No. of mole of C3H6 Mass of C3H6 RMM of C3H6= mass H = 1 ; C = 12; molar gas volume=24 dm3 R.T. ] = of 6.72 dm3 of propene gas C3H6 = [ Relative atomic mass: g = g g x mol mol NEXT Moles: Step 1: No. of Moles when 0.5 dm3 of mole of 25. so Calculate the Study the balanced equation 0.5 2H2O2 → 2H2O + O2 . 2 1 2 volume of oxygen gas O2 produced 1 H2O2 decomposed 1 x 0.5 ÷ 2 NEXT To find Volume of O2 : Step 2: Volume: when 0.5 dm3 of mole of 26. Calculate the given 2000÷4 the volume 0.5 volume 2000 cm3 500 2H2O2 → 2H2O + O2 . 2 of oxygen gas O2 produced H2O2 ÷ 4 = decomposed 24000 cm3 1 x X NEXT no. of moles mol Moles: No. of moles when 200 cm3 of 0.5 mol of 27. 2H2O2 → 2H2O + O2 . Calculate the [ Relative atomic mass: 2H2O2 0.5 → volume 2H2O + O2 of oxygen gas O2 produced H2O2 O = 16 ; H = 1; 24dm3 at room tem ] decomposed NEXT when 200 cm3 of 0.5 mol of 28. 2H2O2 → 2H2O + O2 . Volume No. of moles Moles Calculate the 2000 cm3 [ Relative atomic mass: 2H2O2 0.5 2 → volume 2H2O 2 + O2 0.25 of oxygen gas O2 produced 1 H2O2 O = 16 ; H = 1; 24dm3 at room tem ] cm3 decomposed NEXT when 200 cm3 of 0.5 mol of 29. 2H2O2 → 2H2O + O2 . Volume ÷10 No. of moles Moles Calculate the 2000 cm3 [ Relative atomic mass: 2H2O2 0.5 2 cm3 → volume 2H2O 2 24000 + O2 0.25 of oxygen gas O2 produced 1 H2O2 O = 16 ; H = 1; 24dm3 at room tem ] cm3 cm3 decomposed = = Volume of O2 x cm3 cm3 |