化学问题

四月一日的小皮

原帖由 terencesay 于 14-6-2009 06:52 PM 发表
我想问：
3X{1/Mr(protein)} Ξ 0.00421/58.7
为何protein那里要乘 3？

因为protein里面有３个nickel。。。

cgcy

Will pH affect the reaction rate?

★平常★

新问题：
An organic substance X freezes at -2.4C and boils at 88.0C at a pressure of 1atm.0.270g of X is placed in a flask with a volume of 1.50dm³ and the flask is then immersed in a big beaker that contains a mixture of ice and salt.The flask is then vacuumed using vacuum pump when the temperature of flask reaches room temperature,all the X substance changes to vapour.
a)1.Why is the flask immersed into a big beaker containing salt and ice?
    2.Why is the flask cooled before being vacuumed?
    3.Why do all the X substance becomes vapour at 28C after being vacuumed?
b)When the flask is connected to a manometer, it is found that the vapour pressure in the flask is 5.24KPa at 28C.
   1.By considering the vapour of X acts as an ideal gas, calculate the number of moles of X in the flask.
   2.Determine the relative molecular mass of X.
   3.Calculate the number of X molecules in the flask.

四月一日的小皮

a)1. To lower the temperature of the solution.
    2. To crystillise the organic substance,so that it can exist in solid form.
    3. The pressure of the flask is decreased as vacuum pump is opened. As temperature increase at low pressure, more particle contain high kinetic energy and diffuse out from the substance.This cause organic substance undergo sublimation without entering liquid phase to form vapour.

b)PV = nRT
(5.24 X 1000 )( 1.50 X 10^-3 ) =  n (8.31 )(28 + 273)
                                                   .........
                                                 n  = 3.142 x 10^-3 mol
                    n = m /Mr
                    Mr = 0.270/(3.142x 10^-3)
                    Mr = 85.92

                                            n = no. of molecule / Av
                   no. of molecule = 3.142 x 10^-3 x 6.02 x 10^23
                                              = 1.891 x 10^21 molecules


correct me if i'm wrong,tq.

四月一日的小皮

a)1. To lower the temperature of the solution. 2. To crystillise the organic substance,so that it can exist in solid form. 3. The pressure of the flask is decreased as vacuum pump is opened. As temperature increase at low pressure, more particle contain high kinetic energy and diffuse out from the substance.This cause organic substance undergo sublimation without entering liquid phase to form vapour. b)PV = nRT (5.24 X 1000 )( 1.50 X 10^-3 ) = n (8.31 )(28 + 273) ......... n = 3.142 x 10^-3 mol n = m /Mr Mr = 0.270/(3.142x 10^-3) Mr = 85.92 n = no. of molecule / Av no. of molecule = 3.142 x 10^-3 x 6.02 x 10^23 = 1.891 x 10^21 molecules correct me if i'm wrong,tq.

四月一日的小皮

a)1. To lower the temperature of the solution. 2. To crystillise the organic substance,so that it can exist in solid form. 3. The pressure of the flask is decreased as vacuum pump is opened. As temperature increase at low pressure, more particle contain high kinetic energy and diffuse out from the substance.This cause organic substance undergo sublimation without entering liquid phase to form vapour. b)PV = nRT (5.24 X 1000 )( 1.50 X 10^-3 ) = n (8.31 )(28 + 273) ......... n = 3.142 x 10^-3 mol n = m /Mr Mr = 0.270/(3.142x 10^-3) Mr = 85.92 n = no. of molecule / Av no. of molecule = 3.142 x 10^-3 x 6.02 x 10^23 = 1.891 x 10^21 molecules correct me if i'm wrong,tq.

四月一日的小皮

a)1. To lower the temperature of the solution. 2. To crystillise the organic substance,so that it can exist in solid form. 3. The pressure of the flask is decreased as vacuum pump is opened. As temperature increase at low pressure, more particle contain high kinetic energy and diffuse out from the substance.This cause organic substance undergo sublimation without entering liquid phase to form vapour. b)PV = nRT (5.24 X 1000 )( 1.50 X 10^-3 ) = n (8.31 )(28 + 273) ......... n = 3.142 x 10^-3 mol n = m /Mr Mr = 0.270/(3.142x 10^-3) Mr = 85.92 n = no. of molecule / Av no. of molecule = 3.142 x 10^-3 x 6.02 x 10^23 = 1.891 x 10^21 molecules correct me if i'm wrong,tq.

四月一日的小皮

原帖由 ★平常★ 于 17-6-2009 06:42 PM 发表
新问题：
An organic substance X freezes at -2.4C and boils at 88.0C at a pressure of 1atm.0.270g of X is placed in a flask with a volume of 1.50dm³ and the flask is then immersed in a big beaker ...

a)1. To lower the temperature of the solution. 2. To crystillise theorganic substance,so that it can exist in solid form. 3. The pressureof the flask is decreased as vacuum pump is opened. As temperatureincrease at low pressure, more particle contain high kinetic energy anddiffuse out from the substance.This cause organic substance undergosublimation without entering liquid phase to form vapour.b)PV = nRT (5.24 X 1000 )( 1.50 X 10^-3 ) = n (8.31 )(28 + 273)......... n = 3.142 x 10^-3 mol n = m /Mr Mr = 0.270/(3.142x 10^-3) Mr= 85.92 n = no. of molecule / Av no. of molecule = 3.142 x 10^-3 x 6.02x 10^23 = 1.891 x 10^21 moleculescorrect me if i'm wrong,tq.

四月一日的小皮

a)1. To lower the temperature of the solution. 2. To crystillise the organic substance,so that it can exist in solid form. 3. The pressure of the flask is decreased as vacuum pump is opened. As temperature increase at low pressure, more particle contain high kinetic energy and diffuse out from the substance.This cause organic substance undergo sublimation without entering liquid phase to form vapour. b)PV = nRT (5.24 X 1000 )( 1.50 X 10^-3 ) = n (8.31 )(28 + 273) ......... n = 3.142 x 10^-3 mol n = m /Mr Mr = 0.270/(3.142x 10^-3) Mr = 85.92 n = no. of molecule / Av no. of molecule = 3.142 x 10^-3 x 6.02 x 10^23 = 1.891 x 10^21 molecules correct me if i'm wrong,tq.

四月一日的小皮

卡贴了，惨了～           

★平常★

谢谢你！

walterchoo

when 1g of solid iodine is heated to 1500 K in a closed container of volume 0.5dm^3, the vapour exert a pressure of 150kpa. calculate the degree of dissociation of iodine according to the equation


I2(g) reversible reaction  2I(g)

★平常★

好像有问题了！
怎么都看不到了～