Which phase is heat energy being released?

Tungsten is used in light bulbs because its high...

lara [203]

Tungsten is used in light bulbs because of its high melting point.

It is also used because it has the lowest vapor pressure and greatest tensile strength.

6 0

3 years ago

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When a student mixes 50 mL of 1.0 M HCl and 50 mL of 1.0 M NaOH in a coffee-cup calorimeter, the temperature of the resultant so

zmey [24]

Answer: 54.4 kJ/mol

Explanation:

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=1.0M\times 0.05=0.05mole$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=1.0\times 0.05L=0.05mole$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.05 mole of HCl neutralizes by 0.05 mole of NaOH

Thus, the number of neutralized moles = 0.05 mole

Now we have to calculate the mass of water:

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $50ml+50ml=100ml$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 100ml=100g$

Now we have to calculate the heat absorbed during the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 100 g

$T_{final}$ = final temperature of water = $27.5^0C$

$T_{initial}$ = initial temperature of metal = $21.0^0C$

Now put all the given values in the above formula, we get:

$q=100g\times 4.18J/g^oC\times (27.5-21.0)^0C$

$q=2719.6J=2.72kJ$

Thus, the heat released during the neutralization = 2.72 KJ

Now we have to calculate the enthalpy of neutralization per mole of $HCl$ :

0.05 moles of $HCl$ releases heat = 2.72 KJ

1 mole of $HCl$ releases heat = $\frac{2.72}{0.05}\times 1=54.4KJ$

Thus the enthalpy change for the reaction in kJ per mol of HCl is 54.4 kJ

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3 years ago

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A crime-scene is roped off with yellow tape. The rectangular area is 5.6 meters long 10.75 meters wide. What is the area of the

maksim [4K]

The area is 60.2, to find area it's length times width.

7 0

3 years ago

Why can't methanol, CH3OH, be used as a solvent for sodium amide, NaNH2? Sodium amide is nonpolar and methanol is polar. Sodium

Elodia [21]

Answer: sodium amide undergoes an acid -base reaction

Explanation:

sodium amide is a ionic compound and basically exists as sodium cation and amide anion. Amide anion is highly basic in nature and hence as soon as there is amide anion generated in the solution , Due to its very pronounced acidity it very quickly abstracts the slightly acidic proton available on methanol.

This leads to formation of ammonia and sodium methoxide.

Hence sodium amide reacts with methanol and abstracts its only acidic proton and form ammonia and sodium Methoxide.

Hence the 3rd statement is a corrects statement.

So we cannot use methanol for sodium amide because sodium amide itself would react with methanol and the inherent molecular natur of sodium amide would then change.

The 1st and 2nd statements both are incorrect because both the compounds methanol as well as sodium amide have dipole moments and hence are polar molecules.

The 4th statement is also incorrect as both the molecules have dipole moment and hence there would be ion-dipole forces operating between them.

The following reaction occurs:

NaNH₂+CH₃OH→NH₃+CH₃ONa

4 0

3 years ago

What effect does pneumonia have on the diffusion of O2 and CO2 across the membranes in the lungs? a. slows diffusion b. complete

GarryVolchara [31]

Answer:

a. slows diffusion

Explanation:

Gas exchange on respiratory surfaces in the body (the lungs) occurs through a process known as diffusion. Blood which is low in oxygen and high in carbondioxide (carried from cells) goes through an exchange in the lung's alveoli (where oxygen concentration is high and carbondioxide is low). The oxygen in the alveoli diffuses into the blood, while the carbondioxide in the blood diffuses into the alveoli. This diffusion is possible because of the concentration gradient across the membranes.

Pneumonia is the inflammation of the lungs due to injury or infection. Liquid (pus) accumulates in the alveoli (a natural immune response to the infection or injury), a condition known as pulmonary edema which makes it harder for gases to be exchanged between the blood and the alveoli, thereby making breathing difficult. This slows down diffusion and if the condition is severe enough, can cause a respiratory failure where oxygen levels in the blood are critically low and carbondioxide levels are very high.

5 0

3 years ago