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3 years ago

What is the concentration of hydronium ions after a 100ml solution of 0.02m magnesium hydroxide and 100ml of 0.05m nitric acid?

1 answer:

4 0

$Mg(OH)_2 + 2HNO_3 ---\ \textgreater \ Mg(NO_3)_2 + 2H_2O$

That is the balanced chemical equation.

Before reaction,
milli-moles of Mg(OH)2 = 100 x 0.02 = 2
milli-moles of HNO3 = 100 x 0.05 = 5

After reaction:
Mg(OH)2 is limiting reagent. It will react completely leaving some HNO3 behind.
milli-moles of HNO3 react = 2 x coefficient of HNO3 = 2 x 2 = 4

milli-moles of HNO3 left = 5 -4 = 1

Now, total volume = 100+ 100 = 200 mL

It is asked for hydronium ion concentration, which is basically hydrogen ion conc.
1 HNO3 will dissociate to give 1 H+ ion.

so, milli-moles of H+ = 1

So, concentration of H+ or hydronium(H3O+) = 1 / 200 = 0.005

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A reaction has activation energy of 85kjper mol. What is the effect on the rate of raising the temperature from 20degree to 30 d

DENIUS [597]

Answer: The rate increases 3 times on raising the temperature from 20degree to 30 degree

Explanation:

According to Arrhenius equation with change in temperature, the formula is as follows.

$ln \frac{k_{2}}{k_{1}} = \frac{-E_{a}}{R}[\frac{1}{T_{2}} - \frac{1}{T_{1}}]$

where $k_2$ = rate constant at temp $T_2$

$k_1$ = rate constant at temp $T_1$

$E_a$ = activation energy

R= gas constant

$T_1$ = temperature = $20^0C=(20+273)K=293K$

$T_2$ = temperature = $30^0C=(30+273)K=303K$

$ln \frac{k_{2}}{k_{1}} = \frac{-85\times 1000J/mol}{8.314J/Kmol}[\frac{1}{303} - \frac{1}{293}]$

$ln \frac{k_{2}}{k_{1}}=1.15$

$\frac{k_{2}}{k_{1}}=3$

Thus rate increases 3 times on raising the temperature from 20degree to 30 degree

3 0

3 years ago

What is the volume of 0.640 grams of Oz gas at Standard Temperature and Pressure (STP)?

Ilia_Sergeevich [38]

Answer: The volume of 0.640 grams of $O_{2}$ gas at Standard Temperature and Pressure (STP) is 0.449 L.

Explanation:

Given: Mass of $O_{2}$ gas = 0.640 g

Pressure = 1.0 atm

Temperature = 273 K

As number of moles is the mass of substance divided by its molar mass.

So, moles of $O_{2}$ (molar mass = 32.0 g/mol) is as follows.

$No. of moles = \frac{mass}{molar mass}\\= \frac{0.640 g}{32.0 g/mol}\\= 0.02 mol$

Now, ideal gas equation is used to calculate the volume as follows.

PV = nRT

where,

P = pressure

V = volume

n = no. of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

$PV = nRT\\1.0 atm \times V = 0.02 mol \times 0.0821 L atm/mol K \times 273 K\\V = 0.449 L$

Thus, we can conclude that the volume of 0.640 grams of $O_{2}$ gas at Standard Temperature and Pressure (STP) is 0.449 L.

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3 years ago

What type of reaction occurs when you combine copper (II) chloride whit sodium hydroxide?

Natali5045456 [20]

In this case a double displacement reaction will take place.

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3 years ago

23492u undergoes alpha decay. what is the atomic number of the resulting element.

mash [69]

Alpha decay involves the loss of an alpha particle, aka a helium nucleus. This results in the mass number of the original element decreasing by 4 and the atomic number decreasing by 2. Assuming 23942u is uranium (92), the resulting element's atomic number is 90, making it thorium.

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3 years ago

What happens when heavy exercise results in too much acid in the human body?

White raven [17]

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Hope this helps!

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3 years ago