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musickatia [10]
3 years ago
10

If a student performs an exothermic reaction in a calorimeter, how does the calculated value of ΔH (Hcalc) differ from the actua

l value (Hactual) if the heat exchanged with the calorimeter is not taken into account?
Chemistry
1 answer:
devlian [24]3 years ago
7 0

Answer:

The actual ∆H would be greater than the calculated value of ∆H with no calorimeter.

Explanation:

The amount of heat changed during this process at a fixed pressure is termed Enthalpy

enthalpy change ∆H = ∆E + P∆V

∆E = internal energy change

P = fixed pressure

∆V = change in volume

When energy is absorbed during reaction, it is called endothermic reaction.

Endothermic reaction carried out in the calorimeter and enthalpy change for the reaction. Since we have that

q(surrounding) = q(solution)+q(calorimeter)

Therefore, q(calorimeter) > 0(endothermic).

The actual ∆H would be greater than the calculated value of ∆H with no calorimeter.

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A solution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 211 torr at 39.9∘C. The vap
DaniilM [7]

Answer : This is not an ideal mixture.

Explanation :

Using Raoult's law :

P_{Mixture}=p_{CH_3OH}+p_{H_2O}\\\\P_{Mixture}=x_{CH_3OH}\times p^o_{CH_3OH}+x_{H_2O}\times p^o_{H_2O}

where,

P_{Mixture} = total vapor pressure of mixture

p^o_{CH_3OH} = vapor pressure of pure methanol = 256 torr

p^o_{H_2O} = vapor pressure of pure water = 55.3 torr

x_{H_2O} = mole fraction of water = 0.312  

x_{CH_3OH} = mole fraction of methanol = 1 - 0.312 = 0.688

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

P_{Mixture}=x_{CH_3OH}\times p^o_{CH_3OH}+x_{H_2O}\times p^o_{H_2O}

P_{Mixture}=0.688\times 256torr+0.312\times 55.3torr

P_{Mixture}=193.4torr

From this we conclude that the total vapor pressure of mixture is less than the total given vapor pressure of 211 torr. That means, the interactions between the methanol and water would be weaker than those between the individual substances. So, this is not an ideal mixture.

Hence, this is not an ideal mixture.

3 0
3 years ago
How much energy would it take to heat a section of the copper tubing that weighs about 665.0 g, from 15.71 ∘C to 27.09 ∘C ? Copp
Margarita [4]

Answer:

2914 J

Explanation:

Step 1: Given data

  • Mass of the copper tubing (m): 665.0 g
  • Initial temperature: 15.71 °C
  • Final temperature: 27.09 °C
  • Specific heat of copper (c): 0.3850 J/g.°C

Step 2: Calculate the temperature change

ΔT = 27.09 °C - 15.71 °C = 11.38 °C

Step 3: Calculate the energy required (Q)

We will use the following expression.

Q = c × m × ΔT

Q = 0.3850 J/g.°C × 665.0 g × 11.38 °C

Q = 2914 J

3 0
3 years ago
How many grams of a solution that is 5.2% sucrose by mass are needed to obtain 18g of sucrose
kirill115 [55]

Answer:

346.g of solution

Explanation:

In this case, if we have 5.2 % by mass it means that in <u>100 g of the solution we will have 5.2 g of glucose</u>. Therefore we can do the calculation:

<u>5.2 g of glucose = 100 g of solution</u>

18~g~of~glucose\frac{100~g~of~solution}{5.2~g~of~glucose}=346.15~g~of~solution

So, if we need 8 g of glucose we had to have 346.15 g of solution

This logic can work for all types of solutions. By mass (as in this case), by volume or mass/volume.

I hope it helps!

3 0
4 years ago
Which shows the temperatures of three substances, in order, from greatest to least?water vapor, ice, waterice, water, water vapo
Troyanec [42]
Water vapor >> water >> ice
Water vapor is the gaseous form of water, only achieved when water is heated to a boil or under certain higher pressure circumstances. Water is a liquid in temperatures between 0-100°C (32-212°F). Ice, the solid form of water, occurs when water freezes, at temps below 0°C (32°F).
7 0
4 years ago
Read 2 more answers
Find the ratio of speeds of an electron and a negative hydrogen ion (one having an extra electron) accelerated through the same
Tju [1.3M]

Answer:

42.8

Explanation:

A particle travelling through potential difference V has energy E =qV = 1/2mv²

v = √(2qV / m)

ve = √(2qV / me)

vh = √(2qV / mh)

ve / vh = √( (2qV / me) ÷(2qV / mh) = √ ( mh / me ) where mh = mass of hydrogen ion and me is mass of electron, V voltage is the same, ve is speed of electron and vh is the speed of hydrogen ion

ve / vh  = √ ( mh / me )  = √ ( 1.67 × 10⁻²⁷ kg) / ( 9.11 × 10 ⁻³¹ kg) = 42.8

5 0
3 years ago
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