What should you always do at the end of a lab

To indicate the pH of a substance, one can use a dye that is both an acid and that appears as different colors in its protonated

PIT_PIT [208]

Answer:

The pH of the solution is 7.8

Explanation:

The concentration of the solution is 0.001M and the dye could be in its protonated and deprotonated forms. If the concentration of the protonated form [HA] is 0.0002 M the concentration of the deprotonated form will be the subtraction between the concentration of the bye and the concentration of the protonated form:

[A-] = 0.001M - 0.0002M = 0.0008M

Also, the Henderson-Hasselbalch equation is

$pH = pKa + Log \frac{[A^{-}]}{[HA]}$

this equation shows the dependency between the pH of the solution, the pKa and the concentration of the protonated and deprotonated forms. Thus, replacing in the equation

$pH = 7.2 + Log \frac{0.0008M}{0.0002M} = 7.8$

3 0

3 years ago

A 3.452 g sample containing an unknown amount of a Ce(IV) salt is dissolved in 250.0-mL of 1 M H2SO4. A 25.00 mL aliquot is anal

SOVA2 [1]

Answer:

1,812 wt%

Explanation:

The reactions for this titration are:

2Ce⁴⁺ + 3I⁻ → 2Ce³⁺ + I₃⁻

I₃⁻ + 2S₂O₃⁻ → 3I⁻ + S₄O₆²⁻

The moles in the end point of S₂O₃⁻ are:

0,01302L×0,03428M Na₂S₂O₃ = 4,463x10⁻⁴ moles of S₂O₃⁻. As 2 moles of S₂O₃⁻ react with 1 mole of I₃⁻, the moles of I₃⁻ are:

4,463x10⁻⁴ moles of S₂O₃⁻× $\frac{1molI_{3}^-}{2molS_{2}O_{3}^-}$ = 2,2315x10⁻⁴ moles of I₃⁻

As 2 moles of Ce⁴⁺ produce 1 mole of I₃⁻, the moles of Ce⁴⁺ are:

2,2315x10⁻⁴ moles of I₃⁻× $\frac{2molCe^{4+}}{1molI_{3}^-}$ = 4,463x10⁻⁴ moles of Ce(IV). These moles are:

4,463x10⁻⁴ moles of Ce(IV)× $\frac{140,116g}{1mol}$ = 0,0625 g of Ce(IV)

As the sample has a 3,452g, the weight percent is:

0,0625g of Ce(IV) / 3,452g × 100 = 1,812 wt%

I hope it helps!

5 0

3 years ago

Iron is obtained commercially by the reaction of hematite (Fe2O3) with carbon monoxide. How many grams of iron are produced if 1

kherson [118]

CO is the limiting reactant
( 25.0 x 3 = 75 moles of CO are required)

Moles Fe = 30.0 x 2 / 3 = 20.0
mass Fe = 20.0 x 55.847 g/mol=1117 g 

I'm just saying

5 0

3 years ago

PLEASE ANSWER “Tessa uses a toy slingshot to launch a tennis ball across the park for her dog to fetch. For her first launch, sh

Inessa05 [86]

The third launch ( with 300 N force) had the greatest acceleration of the tennis ball

<h3>Further explanation </h3>

Newton's 2nd law explains that the acceleration produced by the resultant force on an object is proportional and in line with the resultant force and inversely proportional to the mass of the object

∑F = m. a

$\large{\boxed{\bold{a=\frac{\sum F}{m}}}$

F = force, N

m = mass = kg

a = acceleration due to gravity, m / s²

From the above equation it has been shown that the force acting on the object is directly proportional to its acceleration, so the greater the force exerted on the object, the greater the acceleration of the object produced.

8 0

2 years ago

Which of the following substances heats the fastest?

Aneli [31]

Answer:

Zinc

Explanation:

The specific heat capacity can be described as the amount of heat required to raise the temperature of a substance by one degrees Celsius. It is represented by C or S. The greater the carrying capacity of a substance, the more will be the heat required for that substance.

As we can see in the information given in the question, the specific heat capacity of zinc is the lowest as compared to steel, water and aluminium. Hence, zinc is the correct option.

7 0

3 years ago