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  1. For gases at the same temperature and pressure, volume ratio = mole ratio. 2H2(g) + O2(g) → 2H2O(g) Volume ratio H2 : O2 = 2 : 1 Volume of H2 = 100 x 49% = 49 cm3 Volume of O2 needed = 49/2 = 24.5 cm3...

    分類:科學及數學 > 化學 2007年09月11日

  2. mass no. Al=27.0 S=32.1 O=16.0 H=1.0 Avogadro constant = L = 6.02*10^23 formula mass of hydrated aluminium sulphate=27*2+(32.1+16*4)*3+6*(1*2+16)=450.3 no. of moles in sample = 67.5/450.3 = 0.15 mole - the no. of moles of...

    分類:科學及數學 > 化學 2007年01月31日

  3. Suppose that your question refers to % by mass, then: In 1 dm3 of 2 M NaCl solution: No. of moles of NaCl = 2 with mass = 2 x 58.5 = 117 g Mass of water = 1000 g So % by mass of NaCl = 117/(117 + 1000) x 100% = 10.47%

    分類:科學及數學 > 化學 2008年03月20日

  4. Volume * density = mass Volume = mass / density = 23 / 7.86 cm^3 = 2.9262 cm^3 = 2.9262 mm^3 * 10^3 = 2926.2 mm^3

    分類:科學及數學 > 化學 2007年09月27日

  5. 1. NH3 + 2O2 → HNO3 + H2O 2. HNO3 + NH3 → NH4NO3 According to the equations, we should use 8.5 tonnes of ammonia in state one and the other 8.5 tonnes in state 2. (By mole ratio, NH3 : HNO3...

    分類:科學及數學 > 化學 2007年04月19日

  6. Let 1:y be the mole ratio of X to oxygen in the oxide [ (16*y) / (16*y + 74.9) ] x 100% = 24.3% 16y = 3.888 + 18.2007 y = 1.38 ( corr. to 3sig. fig.) 1 : 1.38 ~ 2 : 3 the mole ratio of X to oxygen in the oxide is 2:3

  7. 首先,解條題目: 34g的zine suplphate 於75cm^3的水內,那此溶液的濃度是多少? in 'M' = 濃度單位 moles per cubic decimeter = mol dm ^-3 = Molar 統稱 到高程度時,濃度= M, uM, nM etc...M=1000uM 等. 但你這裡唔駛用. 首先知道zine suplphate...

    分類:科學及數學 > 化學 2007年03月24日

  8. de Brogie wavelength = 6.63x10^-34/square-root[2 x 50x10^3 x 1.6x10^-19 x 9.1x10^-31] m = 5.49x10^-12 m Incident angle = 50/2 deg = 25 deg Hence, 2d.sin(25) = 5.49 x 10^-12 where d is the atomic plane spacing d = 6.5 x 10^-12 m 2013-10-22 23:13:20 補充: Your suppl question. It...

  9. The answer is : A. MgCO3 CaCO3­ and all the metallic carbonates in the four options have similar chemical formulae MCO3. 100 g pure CaCO3 + excess HCl → 44 g CO2 +other products 100 g impure...

    分類:科學及數學 > 化學 2012年07月28日

  10. 1)The total molecular mass= 24.3+32.1+16x4+18x=120.4+18x % of water 18x/(120.4+18x) x100%=51.22 x=7.03 ~=7 2) H+ +OH- ---> H2O In 25cm^3 number of mole of OH-= 7/1000*1.45=0.01015 total number of mole Mg(OH)2 = 0.01015x10/2=0...

    分類:科學及數學 > 化學 2012年04月27日