Questions! (1 Viewer)

[Premus]

1. How do you convert 9.5 ppm to a concentration of mol/L ? (Assuming the density of the solution is 1g/ mL )

2. Explain why ozone has its highest concentrations in the stratophere.

3.Use available evidence to analyse benefits and problems associated with the use of radioactive isotopes in identified industries and medicine. ( Technitium 99m and Cobalt 60)

4. identify data, plan and perform a first-hand investigation to decarbonate soft drink and gather data to measure the mass changes involved and calculate the volume of gas released at 25°C and 100kPa
it would be great if you could outline the method, cause we didnt do it!

Thank you very much!

 

[mervvyn]

1. 9.5ppm = 9.5mg/L, then divide by molar mass of whatever it is you are interested in.

2. Can't remember atm, i think it might be to do with the density of the atmosphere. I don't actually know...

3. Benefits for radioisotopes in medicine: non intrusive diagnosis, non intrusive/ accurate/ powerful treatment, heat free sterilisation
Industry: swift leak detection in pipes, and some others...

4. take a bottle of carbonated water and a bottle of plain water + weigh them, then take caps off and leave for a set period of time, then reweigh and find the mass lost. salt/heat can be used to speed the process of decarbonating. Mass lost from water is evaporation, mass lost from soda water is CO2 and evaporation, compare and calculate.
sorry, i can't recall the specifics atm, hope that helps.

 

[BlackJack]

3. Co-60 is a gamma emitter; the more common usages are leakage detection and the non-intrusive treatment. In industry, thickness detection as well for some metals.

 

[nit]

2.) Ozone isn't stable enough to exist at higher gas pressures (ie concentrations) in lower layers. In the stratosphere, it is decomposed by uv radiation, cfcs etc. Hence it has its highest conc in the stratosphere.

 

[Xayma]

It is also formed through UV radiation the stratosphere being the first place with enough oxygen to it occur.

 

[xeriphic]

3) (adding on from BlackJack) Colbolt-60 beta gamma emitter which is also used in gamma sterilisation for things which otherwise whould be damaged by heat sterilisation such as medical supplies, sterilised bandages and sugical equipments, it is also used to prolong storage life for food as radiation kills the bacteria/mould on fruit and vegetables

 

[tigerchenyanhu]

sorry i am just confused

2.) Ozone isn't stable enough to exist at higher gas pressures (ie concentrations) in lower layers. In the stratosphere, it is decomposed by uv radiation, cfcs etc. Hence it has its highest conc in the stratosphere.

as u say if o3 is decomposed by uv and cfc in the sratosphere how can it has the highest conc ?

 

[Xayma]

Because the UV which forms it doesn't filter down far enough for it to form there, plus its reactivity prevents it from staying long, as with photochemical smog.

 

[~*HSC 4 life*~]

this is a bit sidetracked, but do we ever need to talk about ozone on 'ground level'?

 

[withoutaface]

this is a bit sidetracked, but do we ever need to talk about ozone on 'ground level'?

I think you need to know that it causes smog when its in the troposphere, and is harmful to life at ground level.

 

[~*HSC 4 life*~]

schweeettt

ps chm mon and management is so boring

 

[Paroissien]

Yeah, it is without a doubt the worst of the core topics. Although I would take it over forensics any day. God I hate forensics!