(04.06 LC)

For the reaction shown, calculate how many grams of oxygen form when each quantity of reactant completely reacts.

Nikolay [14]

Explanation:

Molar mass of $KClO_{3}$ = 39.1 + 35.5 + 3(16.0) = 122.6 g

Molar mass of KCl = 39.1 + 35.5 = 74.6 g

Molar mass of $O_{2}$ = 32.0 g

According to the equation, 2 moles of $KClO_{3}$ reacts to give 3 moles of oxygen.

Therefore, 2 (122.6) = 245.2 g of $KClO_{3}$ will give 3 (32.0) = 96.0 g of oxygen. Thus, 245.2 g of $KClO_{3}$ gives 96.0 g of oxygen.

(a) Calculate the amount of oxygen given by 2.72 g of $KClO_{3}$ as follows.

$\frac {96g}{245.2g} \times 2.72 g = 1.06 g$ of $O_{2}$

(b) Calculate the amount of oxygen given by 0.361 g of $KClO_{3}$ as follows.

$\frac {96g}{245.2g} \times 0.361 g = 0.141 g$ of $O_{2}$

c) Calculate the amount of oxygen given by 83.6 kg $KClO_{3}$ as follows.

$\frac {96g}{245.2g} \times 83.6 g = 32.731 kg$ of $O_{2}$

Convert kg into grams as follows.

$\frac{32.731 kg}{1 kg} \times 1000 g$ = 32731 g of $O_{2}$

(d) Calculate the amount of oxygen given by 22.5 mg of $KClO_{3}$ as follows.

$\frac {96g}{245.2g} \times 22.5 mg = 8.79 mg$

Convert mg into grams as follows.

$\frac{8.79 mg}{1 mg}\times 10^{-3} g = 8.79 \times 10^{-3} g$ of $O_{2}$

8 0

3 years ago

2.A calibration curve requires the preparation of a set of known concentrations of CV, which are usually prepared by dieting a s

Aleks04 [339]

Answer:

In order to prepare 10 mL, 5 μM; 2 mL of the 25 μM stock solution will be taken and diluted with water up to 10 mL mark.

In order to prepare 10 mL, 10 μM; 4 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 15 μM; 6 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 20 μM; 8 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

Explanation:

Using the dilution equation:

no of moles before dilution = no of moles after dilution.

Molarity x volume (initial)= Molarity x volume (final).

In order to prepare 10 mL, 5 μM from 25 μM solution,

Final molarity = 5 μM, final volume = 10 mL, initial molarity = 25 μM, initial volume = ?

25 x initial volume = 5 x 10

Initial volume = 50/25

= 2 mL

2 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 10 μM from 25 μM stock,

25 x initial volume = 10 x 10

Initial volume = 100/25 = 4 mL

4 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 15 μM from 25 μM stock,

25 x initial volume = 15 x 10

initial volume = 150/25 = 6 mL

6 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 20 μM from 25 μM stock,

25 x initial volume = 20 x 10

initial volume = 200/25 = 8 mL

8 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

6 0

3 years ago

HEEEEELP ASAPP IM AWARDING 30 points!!!!

alexira [117]

Answer:

$\rm S^{2-}$ .

Explanation:

Based on the electron configuration of this ion, count the number of electrons in this ion in total:

$2 + (2 + 6) + (2 + 6) = 18$ .

Each electron has a charge of $(-1)$ .

Atoms are neutral and have $0$ charge. However, when an atom gains one extra electron, it becomes an ion with a charge of $(-1)$ . Likewise, when that ion gains another electron, the charge on this ion would become $(-2)$ .

The ion in this question has a charge of $(-2)$ . In other words, this ion is formed after its corresponding atom gains two extra electrons. This ion has $18$ electrons in total. Therefore, the atom would have initially contained $18 - 2 = 16$ electrons. The atomic number of this atom would be $16$ .

Refer to a modern copy of the periodic table. The element with an atomic number of $16$ is sulphur with atomic symbol $\rm S$ . To denote the ion, place the charge written backwards (" $2-$ " for a charge of $(-2)$ ) as the superscript of the atomic symbol:

$\rm S^{2-}$ .

5 0

3 years ago

Read 2 more answers

A 20 g granite boulder absorbs 300.2 Joules of energy from the Sun, resulting in its temperature

s344n2d4d5 [400]

Answer:

19 °C

Explanation:

Step 1: Given and required data

Mass of granite (m): 20 g

Heat absorbed (Q): 300. 2 J

Specific heat capacity of granite (c): 0.790 J/g.°C

Step 2: Calculate the temperature change (ΔT)

We will use the following expression.

Q = c × m × ΔT

ΔT = Q/c × m

ΔT = 300.2 J/(0.790 J/g.°C) × 20 g = 19 °C

3 0

3 years ago

How can trace fossils provide info on how the organism lived

iragen [17]

Fossils provide a window in Earth's history by showing us how they existed in the past. They can be dated through several ways and can show us how animals and plants have evolved over millions of years. Also, fossils can help us better understand ancient disasters by the inclusion of elements (such as volcanic ash or dust from major space object impacts) and how they affected the life on earth)

5 0

3 years ago