Answer:
a) Endothermic
b) T₂ = 53.1 ºC
Explanation:
a) We are told that when the ammonium nitrate dissolves in water the pack gets cold so the system is absorbing heat from the surroundings and by definition it is an endothermic process.
b) Recall that the heat, Q, is given by the formula:
Q = mcΔT where m is the mass of water,
c is the specific heat of water, and
ΔT is the change in temperature
We can determine the value for Q since we are given the heat of solution for the ammonium nitrate. From there we can calculate ΔT and finally answer our question.
Molar mass NH₄NO₃ = 80.04 g/mol
moles NH₄NO₃ = 50.0 g/ 80.04 g/mol = 0.62 mol
Q = 25.4 kJ/mol x 0.62 mol = 15.87 kJ = 15.87 kJ x 1000 J = 1.59 x 10⁴ J
Q = mcΔT ⇒ ΔT = Q/mc
ΔT = 1.59 x 10⁴ J/ (135 g x 4.184 J/gºC ) = 28.1 ºC
T₂- T₁ = ΔT ⇒ T₂ = ΔT + T₁ = 28.1 ºC +25.0 ºC = 53.1 ºC
Answer:
Cleaning up oil spills and metal contaminates in a low-impact, sustainable and inexpensive manner remains a challenge for companies and governments globally.
But a group of researchers at UW–Madison is examining alternative materials that can be modified to absorb oil and chemicals. If further developed, the technology may offer a cheaper and “greener” method to absorb oil and heavy metals from water and other surfaces.
Aerogels, which are highly porous materials and the lightest solids in existence, are already used in a variety of applications, ranging from insulation and aerospace materials to thickening agents in paints. The aerogel prepared in Gong’s lab is made of cellulose nanofibrils (sustainable wood-based materials) and an environmentally friendly polymer. Furthermore, these cellulose-based aerogels are made using an environmentally friendly freeze-drying process without the use of organic solvents.
It’s the combination of this “greener"material and its high performance that got Gong’s attention.
“For this material, one unique property is that it has superior absorbing ability for organic solvents — up to nearly 100 times its own weight,” she says. “It also has strong absorbing ability for metal ions.”
Treating the cellulose-based aerogel with specific types of silane after it is made through the freeze-drying process is a key step that gives the aerogel its water-repelling and oil-absorbing properties.
Answer:The functional groups in an organic compound can frequently be deduced from its infrared absorption spectrum. A compound, C5H10O2, exhibits strong, broad absorption across the 2500-3200 cm^1 region and an intense absorption at 1715 cm'^-1. Relative absorption intensity: (s)=strong, (m)-medium, (w) weak. What functional class(cs) docs the compound belong to List only classes for which evidence is given here. Attach no significance to evidence not cited explicitly. Do not over-interpret exact absorption band positions. None of your inferences should depend on small differences like 10 to 20 cm^1. The functional class(es) of thla compound is(are) alkane (List only if no other functional class applies.) alkene terminal alkyne internal alkyne arene alcohol ether amine aldehyde or ketone carboxylic acid ester nitr
Answer:
Look at sheet
Explanation:
Ight so like I'm too lazy to type this out just look at my work. Idk why it works I just know it works
Lower the melting point
Explanation:
Salts helps to melt road by lowering the melting point. It acts as an impurity and generally, impurities low the melting point of substances.
Salts are used as an antifreeze.
- Water freezes at 0°C and forms ice/snow which can impede human and vehicular movement.
- When salt is added, it causes the depression of the freezing point by lowering it further.
- The freezing point is pegged back at -6°C.
- This way it takes more low temperature to freeze the water.
- The salt acts as an impurity and causes the depression of melting point and widening of the melting range.
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