when a chemical change occurs, if the temperature drops, what effect will it have on the rate of chemical reaction?

A 0.100 M oxalic acid, HO2CCO2H, solution is titrated with 0.100 M KOH. Calculate the pH when 25.00 mL of oxalic acid solution i

____ [38]

Answer:

pH = 4.09

Explanation:

molarity of oxalic acid in the solution

= 0.1 x 25 / (25 + 35)

= 0.0417 M

molarity of NaOH in the solution

= 0.1 x 35 / (25 +35)

= 0.0583 M

H2C2O4 + NaOH -------------------> NaHC2O4 + H2O

0.0417 0.0583 0 0

0 0.0166 0.0417

now second acid -base titration

NaHC2O4 + NaOH -------------------> Na2C2O4 + H2O

0.0417 0.0166 0 0

0.0251 0 0.0166 ---

now

pH = pKa2 + log [Na2C2O4 / NaHC2O4]

pH = 4.27 + log (0.0166 / 0.0251)

pH = 4.09

3 0

3 years ago

luminum and oxygen react according to the following equation: 4Al(s) +3O2(g) --> 2Al2O3(s) What mass of Al2O3, in grams, can

Slav-nsk [51]

Answer: 8.7 grams

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{4.6g}{27g/mol}=0.17moles$

$4Al(s)+3O_2(g)\rightarrow 2Al_2O_3(s)$

As oxygen is in excess, Aluminium is the limiting reagent and limits the formation of products.

According to stoichiometry:

4 moles of aluminium give = 2 moles of $Al_2O_3(s)$

Thus 0.17 moles of aluminium give= $\frac{2}{4}\times 0.17=0.085mol$

Mass of $Al_2O_3=moles\times {\text {molar mass}}=0.085\times 102g/mol=8.7g$

Thus the mass of $Al_2O_3(s)$ is 8.7 grams

8 0

3 years ago

Answer these questions based on 234.04360 as the atomic mass of thorium-234. The masses for the subatomic particles are given. R

Scilla [17]

How many protons does Thorium have? 90

How many neutrons does Thorium-234 have? 144

Calculate the mass defect for the isotope thorium-234 1.85864 amu

4 0

3 years ago

Read 2 more answers

How did oxygen first enter Earth's atmosphere?

forsale [732]

Answer:

I think c biological processes

8 0

3 years ago

What is the molarity of a solution containing 8.9 g of NaOH in 550. mL of NaOH solution?

bulgar [2K]

Answer:

0.4 M

Explanation:

Molarity is defined as moles of solute, which in your case is sodium hydroxide,

NaOH

, divided by liters of solution.

molarity

=

moles of solute

liters of solution

Notice that the problem provides you with the volume of the solution, but that the volume is expressed in milliliters,

mL

.

Moreover, you don't have the number of moles of sodium hydroxide, you just have the mass in grams. So, your strategy here will be to

determine how many moles of sodium hydroxide you have in that many grams

convert the volume of the solution from milliliters to liters

So, to get the number of moles of solute, use sodium hydroxide's molar mass, which tells you what the mass of one mole of sodium hydroxide is.

7

g

⋅

1 mole NaOH

40.0

g

=

0.175 moles NaOH

The volume of the solution in liters will be

500

mL

⋅

1 L

1000

mL

=

0.5 L

Therefore, the molarity of the solution will be

c

=

n

V

c

=

0.175 moles

0.5 L

=

0.35 M

Rounded to one sig fig, the answer will be

c

=

0.4 M

Explanation:

6 0

3 years ago