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3 years ago

Three Stoichiometry Questions

Chemistry

1 answer:

andrezito [222]3 years ago

4 0

Answer:

Explanation:

Given data:

Mass of aluminium = 2.5 g

Mass of oxygen = 2.5 g

Mass of aluminium oxide = 3.5 g

Percent yield = ?

Solution:

Chemical equation:

4Al + 3O₂ → 2Al₂O₃

Number of moles of Al:

Number of moles = mass/ molar mass

Number of moles = 2.5 g/ 27 g/mol

Number of moles = 0.09 mol

Number of moles of oxygen:

Number of moles = mass/ molar mass

Number of moles = 2.5 g/ 32 g/mol

Number of moles = 0.08 mol

Now we will compare the moles of aluminium oxide with aluminium and oxygen.

Al ; Al₂O₃

4 : 2

0.09 : 2/4×0.09 = 0.045

O₂ : Al₂O₃

3 : 2

0.08 : 2/3 ×0.08 = 0.053

The number of moles of aluminium oxide produced by Al are less so it will limiting reactant.

Mass of aluminium oxide:

Mass = number of moles × molar mass

Mass = 0.045 × 101.96 g/mol

Mass = 4.6 g

Percent yield:

Percent yield = actual yield / theoretical yield ×100

Percent yield = 3.5 g / 4.6 ×100

Percent yield = 76.1%

Given data:

Mass of copper produced = 3.47 g

Mass of aluminium = 1.87 g

Percent yield = ?

Solution:

Chemical equation:

2Al + 3CuSO₄ → Al₂(SO₄)₃ + 3Cu

Number of moles of Al:

Number of moles = mass/ molar mass

Number of moles = 1.87 g/ 27 g/mol

Number of moles = 0.07 mol

Now we will compare the moles of copper with aluminium.

Al ; Cu

2 : 3

0.07 : 3/2×0.09 = 0.105

Mass of copper:

Mass = number of moles × molar mass

Mass = 0.105 × 63.55 g/mol

Mass = 6.67 g

Percent yield:

Percent yield = actual yield / theoretical yield ×100

Percent yield = 3.47 g / 6.67 × 100

Percent yield = 52%

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Though alchemy was not a part of seven liberal arts curriculum in per-modern Europe education, alchemical experiments caused imp

Galina-37 [17]

Answer:

The goal of the alchemists, who practiced from 400-1400 AD, was to transmute common elements (like lead) into gold. The alchemists used symbols to identify elements, and made many important discoveries which led to the development of the modern science of chemistry.

Explanation:

Alchemists were contracted by the elite for practical purposes related to mining, medical services, and the production of chemicals, medicines, metals, and gemstones. Entrepreneurial opportunities were common for the alchemists of Renaissance Europe.

Alchemy was based on the belief that there are four basic elements in nature: air, fire, water and earth. Alchemy is an ancient practice shrouded in mystery and secrecy. Its practitioners mainly sought to turn lead into gold, a quest that has captured the imaginations of people for thousands of years

The difference between alchemy and modern chemistry is alchemy is based on a mystic, supernatural view of reality, whereas chemistry assumes reality is basically natural. That makes a huge difference, and chemistry would never have gotten very far if it had stuck with the old metaphysics.

Despite these connotations of the mythic and mystical, alchemical practice played an important role in the evolution of modern science to discover the relationship of humans to the cosmos and use that understanding to improve the human spirit. Alchemy was scientific but it was also a spiritual tradition.

5 0

3 years ago

A 1.775g sample mixture of potassium hydrogen carbonate is decomposed by heating. if the mass loss is 0.275g what is the percent

Marina86 [1]

A 1.775g sample mixture of KHCO₃ is decomposed by heating. if the mass loss is 0.275g, the mass percentage of KHCO₃ is 70.4%.

<h3>What is a decomposition reaction?</h3>

A decomposition reaction can be defined as a chemical reaction in which one reactant breaks down into two or more products.

Step 1: Write the balanced equation for the decomposition of KHCO₃.

2 KHCO₃(s) → K₂CO₃(s) + CO₂(g) + H₂O(l)

The mass loss of 0.275 g is due to the gaseous CO₂ that escapes the sample.

Step 2: Calculate the mass of KHCO₃ that formed 0.275 g of CO₂.

In the balanced equation, the mass ratio of KHCO₃ to CO₂ is 200.24:44.01.

0.275 g CO₂ × 200.24 g KHCO₃/44.01 g CO₂ = 1.25 g KHCO₃

Step 3: Calculate the mass percentage of KHCO₃ in the sample.

There are 1.25 g of KHCO₃ in the 1.775 g sample.

%KHCO₃ = 1.25 g/1.775 g × 100% = 70.4%

A 1.775g sample mixture of KHCO₃ is decomposed by heating. if the mass loss is 0.275g, the mass percentage of KHCO₃ is 70.4%.

Learn more about decomposition reactions here: brainly.com/question/14219426

7 0

2 years ago

stomach acid contains dilute hydrochloric acid write a chemical equation to show the neutralization of stomach acid by milk of m

Eddi Din [679]

Answer:

Mg(OH)2(s) + 2HCl(aq) → 2H2O(l) + MgCl2(aq)

Explanation:

4 0

3 years ago

What is the pH of a solution with a concentration of 1.8 × 10-4 molar H3O+?

Andre45 [30]

PH is defined as the negative log of Hydrogen ion concentration. Mathematically we can write this as:

$pH=-log[H^{+}]=-log[H_{3}O]$

We are given the concentration of $H_{3}O$ . Using the value in formula, we get:

$pH=-log[1.8*10^{-4}]=3.745$

Therefore, the pH of the solution will be 3.745

8 0

3 years ago

What mass of water is produced by the combustion 1.2 x 10^26 molecules of butane ?

podryga [215]

Answer:

17.934 kg of water

Explanation:

If balanced equation is not given; this format can come in handy.

For any alkane of the type : CₙH₂ₙ₊₂ , it's combustion reaction will follow:

2CₙH₂ₙ₊₂ + (3n+1) O₂ → (2n)CO₂ + 2(n+1) H₂O

For butane:

2C₄H₁₀(g) + 13O₂(g) → 8CO₂(g) + 10H₂O(l)

2 moles of butane gives 10 moles of water.

1 mol of any substance has Avogadro number(N) of molecules in it( 6.022 x 10²³)

Mass of 1 mole of any substance is equal to it's molar mass

So, if 2 x N molecules of butane gives 10 x 18 g of water.

Then 1.2 x 10²⁶ molecules will give:

$\frac{1.2 \times 10^{26} \times 180}{2 \times 6.022 \times 10^{23}}$

= 17.934 x 10³ g of water

= 17.934 kg of water

5 0

3 years ago