If a sample of matter cannot be separated by physical means, what can be said with certainty about that sample?

A 115.0-g sample of oxygen was produced by heating 400.0 g of potassium chlorate.2KClO3 Right arrow. 2KCI + 3O2What is the perce

STALIN [3.7K]

Answer:

73.4% is the percent yield

Explanation:

2KClO₃ → 2KCl + 3O₂

This is a decomposition reaction, where 2 moles of potassium chlorate decompose to 2 moles of potassium chloride and 3 moles of oxygen.

We determine the moles of salt: 400 g . 1. mol /122.5g= 3.26 moles of KClO₃

In the theoretical yield of the reaction we say:

2 moles of potassium chlorate can produce 3 moles of oxygen

Therefore, 3.26 moles of salt, may produce (3.26 . 3) /2 = 4.89 moles of O₂

The mass of produced oxygen is: 4.89 mol . 32 g /1mol = 156.6g

But, we have produced 115 g. Let's determine the percent yield of reaction

Percent yield = (Produced yield/Theoretical yield) . 100

(115g / 156.6g) . 100 = 73.4 %

5 0

3 years ago

Which symbol can be used to indicate the pressure at which a chemical reaction is carried out? 25 degrees Celsius over a right a

jolli1 [7]

Answer:

2 atm

Explanation:

Chemical reactions are carried out at a certain rate. Sometimes that rate is quite slow, so we want to speed things up, which is usually used by increasing temperature, increasing pressure or adding a catalyst (a substance that increases the rate without changing itself).

If this is the case, then, when writing a chemical equation, we state these special conditions over a right arrow.

Now let's look at the answers:

- 25°C is a value and unit of temperature

- ∆ is a symbol that denotes change

- 2 atm is a value and unit of pressure (atmosphere is old unit for pressure)

- Pt is a chemical symbol for platinum, an element often used as a catalyst.

So, the correct answer is C) 2 atm

7 0

4 years ago

Read 2 more answers

What is the maximum number of grams of copper that could be produced by the reaction of 30.0 of copper oxide with excess methane

Solnce55 [7]

Answer: 24.13 g Cu

Explanation:

<u>Given for this question:</u>

M of CuO = 30 g

m of CuO = 79.5 g/mol

Number of moles of CuO = (given mass ÷ molar mass) = (30 ÷ 79.5) mol

= 0.38 mol

The max number of CuO (s) that can be produced by the reaction of excess methane can be solved with this reaction:

CuO(s) + CH4(l) ------> H2O(l) + Cu(s) + CO2(g)

The balanced equation can be obtained by placing coefficients as needed and making sure the number of atoms of each element on the reactant side is equal to the number of atoms of each element on the product side

4CuO(s) + CH4(l) ----> 2H2O(l) + 4Cu(s) + CO2(g)

From the stoichiometry of the balanced equation:

4 moles of CuO gives 4 moles of Cu

1 mole of CuO gives 1 mol of Cu

0.38 mol of CuO gives 0.38 mol of Cu

Therefore, the grams of Cu that can be produced = 0.38 × molar mass of Cu

= 0.38 × 63.5 g

= 24.13 grams

Therefore, 24.13 grams of copper could be produced by the reaction of 30.0 of copper oxide with excess methane

4 0

2 years ago

A balloon with a volume of 38.2 L at 91 psi is allowed to expand into a larger can with a total volume of 77.4 L. What is the pr

adelina 88 [10]

Answer:

<u>45 psi</u>

Explanation:

a) V₁ = 38.2 liter

b) P₁ = 91 psi

c) V₂ = 77.4 liter

d) P₂ = ?

<u>2) Formula:</u>

According to Boyle's law, at constant temperature, the pressure and volume of a fixed amount of gas are inversely related:

PV = constant ⇒P₁V₁ = P₂V₂

<u>3) Solution:</u>

Solve for the unknown: P₂ = P₁V₁ /v₂

Substitute the values: V₂ = 91 psi × 38.2 liter / 77.4 liter = 44.9 9si ≈ 45 psi.

7 0

4 years ago

A scientist produces zinc iodide (zni2). (a) calculate the minimum mass of zinc that needs to be added to 0.500 g of iodine so t

harina [27]

The minimum mass of Zinc, Zn that needs to be added to 0.500 g of iodine so that the iodine fully reacts is 0.128 g

<h3>Balanced equation </h3>

Zn + I₂ —> ZnI₂

Molar mass of Zn = 65 g/mol

Mass of Zn from the balanced equation = 1 × 65 = 65 g

Molar mass of I₂ = 127 × 2 = 254 g/mol

Mass of I₂ from the balanced equation = 1 254 = 254 g

SUMMARY

From the balanced equation above,

254 g of I₂ required 65 g of Zn

<h3>How to determine the mass of Zn needed </h3>

From the balanced equation above,

254 g of I₂ required 65 g of Zn

Therefore,

0.5 g of I₂ will require = (0.5 × 65) / 254 = 0.128 g of Zn

Thus, the minimum mass of Zn required is 0.128 g

Learn more about stoichiometry:

brainly.com/question/14735801

4 0

3 years ago