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max2010maxim [7]
3 years ago
5

What were the constraints on Nils Bohlin’s solution to safer seatbelts?

Chemistry
1 answer:
ArbitrLikvidat [17]3 years ago
4 0

Answer:

He realized he needs to have the upper body and lower body held in place and needed the buckle as far down beside the person's hip so it could hold the body properly

Explanation: ''I realized both the upper and lower body must be held securely in place with one strap across the chest and one across the hips,'' Mr. Bohlin once said. ''The belt also needed an immovable anchorage point for the buckle as far down beside the occupant's hip, so it could hold the body properly during a collision.

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lisabon 2012 [21]
I hope you understood
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6 0
3 years ago
Constructive and destructive process. ​
Aleks [24]

Answer:

again here

Explanation:

Collection and analysis of data indicate that constructive forces include crustal deformation, faulting, volcanic eruption and deposition of sediment, while destructive forces include weathering and erosion. I can explain how constructive and destructive forces affect the nature of landforms on Earth.

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8 0
3 years ago
At what temperature is the following reaction feasible: HCl(g) + NH3(g) -> NH4Cl(s)?
Nutka1998 [239]
Energy is distributed not just in translational KE, but also in rotation, vibration and also distributed in electronic energy levels (if input great enough, bond breaks).

All four forms of energy are quantised and the quanta ‘gap’ differences increases from trans. KE ==> electronic.

Entropy (S) and energy distribution: The energy is distributed amongst the energy levels in the particles to maximise their entropy.

Entropy is a measure of both the way the particles are arranged AND the ways the quanta of energy can be arranged.

We can apply ΔSθsys/surr/tot ideas to chemical changes to test feasibility of a reaction:

ΔSθtot = ΔSθsys +  ΔSθsurr

ΔSθtot must be >=0 for a chemical change to be feasible.

For example: CaCO3(s) ==> CaO(s) + CO2(g) 

ΔSθsys = ΣSθproducts – ΣSθreactants 

ΔSθsys = SθCaO(s) + SθCO2(g) – SθCaCO3(s) 

ΔSθsurr is –ΔHθ/T(K) and ΔH is very endothermic (very +ve),

Now ΔSθsys is approximately constant with temperature and at room temperature the ΔSθsurr term is too negative for ΔSθtot to be plus overall.

But, as the temperature is raised, the ΔSθsurr term becomes less negative and eventually at about 800oCΔSθtot becomes plus overall (and ΔGθ becomes negative), so the decomposition is now chemically, and 'commercially' feasible in a lime kiln.

CaCO3(s) ==> CaO(s) + CO2(g)  ΔHθ = +179 kJ mol–1  (very endothermic)

This important industrial reaction for converting limestone (calcium carbonate) to lime (calcium oxide) has to be performed at high temperatures in a specially designed limekiln – which these days, basically consists of a huge rotating angled ceramic lined steel tube in which a mixture of limestone plus coal/coke/oil/gas? is fed in at one end and lime collected at the lower end. The mixture is ignited and excess air blasted through to burn the coal/coke and maintain a high operating temperature.
ΔSθsys = ΣSθproducts – ΣSθreactants
ΔSθsys = SθCaO(s) + SθCO2(g) – SθCaCO3(s) = (40.0) + (214.0) – (92.9) = +161.0 J mol–1 K–1
ΔSθsurr is –ΔHθ/T = –(179000/T)
ΔSθtot = ΔSθsys +  ΔSθsurr
ΔSθtot = (+161) + (–179000/T) = 161 – 179000/T
If we then substitute various values of T (in Kelvin) you can calculate when the reaction becomes feasible.
For T = 298K (room temperature)

ΔSθtot = 161 – 179000/298 = –439.7 J mol–1 K–1, no good, negative entropy change

For T = 500K (fairly high temperature for an industrial process)

ΔSθtot = 161 – 179000/500 = –197.0, still no good

For T = 1200K (limekiln temperature)

ΔSθtot = 161 – 179000/1200 = +11.8 J mol–1 K–1, definitely feasible, overall positive entropy change

Now assuming ΔSθsys is approximately constant with temperature change and at room temperature the ΔSθsurr term is too negative for ΔSθtot to be plus overall. But, as the temperature is raised, the ΔSθsurr term becomes less negative and eventually at about 800–900oC ΔSθtot becomes plus overall, so the decomposition is now chemically, and 'commercially' feasible in a lime kiln.
You can approach the problem in another more efficient way by solving the total entropy expression for T at the point when the total entropy change is zero. At this point calcium carbonate, calcium oxide and carbon dioxide are at equilibrium.
ΔSθtot–equilib = 0 = 161 – 179000/T, 179000/T = 161, T = 179000/161 = 1112 K

This means that 1112 K is the minimum temperature to get an economic yield. Well at first sight anyway. In fact because the carbon dioxide is swept away in the flue gases so an equilibrium is never truly attained so limestone continues to decompose even at lower temperatures.

8 0
3 years ago
Read 2 more answers
Which of the reactions below are catalyzed? Check all that apply.
Verdich [7]

Answer:

B. Salt, NaCl, is produced by the process of evaporation of seawater or brine. If the surface area of the water is increased, the same volume of water evaporates faster.

C. The Haber process combines hydrogen and nitrogen to make ammonia. The two gases are passed through a reactor under pressure and at high temperatures. If iron is added to the reactor, the yield of ammonia increases.

Explanation:

Evaporation of water is responsible for the production of sodium chloride also known as table salt. Sodium and chlorine are present in water. When more evaporation of water occurs, sodium and chlorine come close together forming sodium chloride. Haber process is responsible for the production of ammonia which is used as fertilizer. For speed up the process, catalyst is used such as iron in order to complete the reaction in less time. Iron binds hydrogen and nitrogen with each other.

7 0
3 years ago
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Which of the following Substances would have the highest vapor pressure at 298 K?
elena-14-01-66 [18.8K]
The answer is D. hope I was right
7 0
3 years ago
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