True or false(Internal forces act on the outside of an object, and external forces act within an object.)

At 20°C the vapor pressure of benzene (C6H6) is 75 torr, and that of toluene (C7H8) is 22 torr. Assume that benzene and toluene

valina [46]

Answer: The mole fraction of benzene will be 0.34 and mole fraction of toluene is 0.66

Explanation:

According to Raoult's law, the vapor pressure of a component at a given temperature is equal to the mole fraction of that component multiplied by the vapor pressure of that component in the pure state.

$p_1=x_1p_1^0$ and $p_2=x_2P_2^0$

where, x = mole fraction in solution

$p^0$ = pressure in the pure state

According to Dalton's law, the total pressure is the sum of individual pressures.

$p_{total}=p_1+p_2\\$ $p_{total}=x_{benzene}p_{benzene}^0+x_{toluene}P_{toluene}^0$

$x_{benzene}=x$ ,

$x_{toluene}=1-x_{benzene}=1-x$ ,

$p_{benzene}^0=75torr$

$p_{toluene}^0=22torr$

$p_{total}=40torr$

$40=x\times 75+(1-x)\times 22$

$x=0.34$

Thus (1-x0 = (1-0.34)=0.66

Thus the mole fraction of benzene will be 0.34 and that of toluene is 0.66

8 0

3 years ago

Why do atoms of nonmetals form anions? Support your answer with an example.

Papessa [141]

Nonmetals form negatively charged ions, or anions. They do this because they need to gain one to three electrons in order to achieve an octet of valence electrons, making them isoelectronic with the noble gas at the end of the period to which they belong.

5 0

3 years ago

Explain why the concentrations of a mixture at equilibrium are constant as a function of time

Paraphin [41]

The concentrations of a mixture at equilibrium are constant as a function of time because the <span>e forward reaction proceeds at the same rate as the reverse reaction.</span>

8 0

3 years ago

A 0.25-mol sample of a weak acid with an unknown Pka was combined with 10.0-mL of 3.00 M KOH, and the resulting solution was dil

Masteriza [31]

Answer : The value of $pK_a$ of the weak acid is, 4.72

Explanation :

First we have to calculate the moles of KOH.

$\text{Moles of }KOH=\text{Concentration of }KOH\times \text{Volume of solution}$

$\text{Moles of }KOH=3.00M\times 10.0mL=30mmol=0.03mol$

Now we have to calculate the value of $pK_a$ of the weak acid.

The equilibrium chemical reaction is:

$HA+KOH\rightleftharpoons HK+H_2O$

Initial moles 0.25 0.03 0

At eqm. (0.25-0.03) 0.03 0.03

= 0.22

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[HK]}{[HA]}$

Now put all the given values in this expression, we get:

$3.85=pK_a+\log (\frac{0.03}{0.22})$

$pK_a=4.72$

Therefore, the value of $pK_a$ of the weak acid is, 4.72

7 0

3 years ago

How many moles is in 2.52*10^24 molecules of water?

nataly862011 [7]

Hi friend
--------------
Your answer
-------------------

Water = H2O

Number of molecules in one mole of water = 6.022 × 10²³ [Avogadro's constant]

Given number of molecules = 2.52 × 10²³

So,
------

Number of moles =
$\frac{2.52 \times 10 {}^{24} }{6.022 \times 10 {}^{23} } \\ \\ = 4.184 \: (approximately)$

HOPE IT HELPS

3 0

3 years ago