18.9 = 0.580/V Pls answer

Chromium is dissolved in sulfuric acid according to the following equation: Cr + H2SO4 ⇒ Cr2 (SO4) 3 + H2

Usimov [2.4K]

Answer:

$\large \boxed{\text{a)188.4 g; b) 98.67 $\, \%$}}$

Explanation:

We will need a balanced chemical equation with masses and molar masses, so, let's gather all the information in one place.

Mᵣ: 98.08 392.18

2Cr + 3H₂SO₄ ⟶ Cr₂(SO₄)₃ + 3H₂

To solve the stoichiometry problem, you must

Use the molar mass of H₂SO₄ to convert the mass of H₂SO₄ to moles of H₂SO₄
Use the molar ratio to convert moles of H₂SO₄ to moles of Cr₂(SO₄)₃
Use the molar mass of Cr₂(SO₄)₃ to convert moles of Cr₂(SO₄)₃ to mass of Cr₂(SO₄)₃

a) Mass of Cr₂(SO₄)₃

(i) Mass of pure H₂SO₄

$\text{Mass of pure} = \text{165 g impure} \times \dfrac{\text{85.67 g pure} }{\text{100 g impure}} = \text{141.36 g pure}$

(ii) Moles of H₂SO₄

$\text{Moles of H$_{2}$SO}_{4} = \text{141.36 g H$_{2}$SO}_{4} \times \dfrac{\text{1 mol H$_{2}$SO}_{4}}{\text{98.08 g H$_{2}$SO}_{4}} = \text{1.441 mol H$_{2}$SO}_{4}$

(iii) Moles of Cr₂(SO₄)₃

The molar ratio is 1 mol Cr₂(SO₄)₃:3 mol H₂SO₄ $\text{Moles of Cr$_{2}$(SO$_{4}$)}_{3} = \text{1.441 mol H$_{2}$SO}_{4} \times \dfrac{\text{1 mol Cr$_{2}$(SO$_{4}$)}_{3}}{\text{3 mol H$_{2}$SO}_{4}} = \text{0.4804 mol Cr$_{2}$(SO$_{4}$)}_{3}$

(iv) Mass of Cr₂(SO₄)₃ $\text{Mass of Cr$_{2}$(SO$_{4}$)}_{3} = \text{0.4804 mol Cr$_{2}$(SO$_{4}$)}_{3} \times \dfrac{\text{392.18 g Cr$_{2}$(SO$_{4}$)}_{3}}{\text{1 mol Cr$_{2}$(SO$_{4}$)}_{3}} = \textbf{188.4 g Cr$_{2}$(SO$_{4}$)}_{3}\\\text{The mass of Cr$_{2}$(SO$_{4}$)$_{3}$ formed is $\large \boxed{\textbf{188.4 g}}$}$

b) Percentage yield

It is impossible to get a yield of 485.9 g. I will assume you meant 185.9 g.

$\text{Percentage yield} = \dfrac{\text{Actual yield}}{\text{Theoretical yield}} \times 100 \, \% = \dfrac{\text{185.9 g}}{\text{188.4 g}} \times 100 \, \% = \mathbf{98.67 \, \%}\\\\\text{The percentage yield is $\large \boxed{\mathbf{98.67 \, \%}}$}$

7 0

4 years ago

A 0.500 g sample of phosphorous vapor exerts a pressure of 550. torr in a 73.1 mL container at 489∘C. What is the molar mass?

Korolek [52]

Answer:

Molar mass= 78.8gmol-1

Explanation:

P= 550torr, V= 0.0732dm3, m= 0.5g , R= 8.314, T= 273+489= 762K

Applying

PV= m/Mm×(R×T)

Substitute and Simplify

Mm= 78.8gmol-1

7 0

3 years ago

Which of the following best describe the chronological way of specimen preparation?

nata0808 [166]

Answer:

There are many reasons to examine human cells and tissues under the microscope. Medical and biological research is underpinned by knowledge of the normal structure and function of cells and tissues and the organs and structures that they make up. In the normal healthy state, the cells and other tissue elements are arranged in regular, recognizable patterns. Changes induced by a wide range of chemical and physical influences are reflected by alterations in the structure at a microscopic level, and many diseases are characterized by typical structural and chemical abnormalities that differ from the normal state. Identifying these changes and linking them to particular diseases is the basis of histopathology and cytopathology, important specializations of modern medicine. Microscopy plays an important part in haematology (the study of blood), microbiology (the study of microorganisms including parasites and viruses), and more broadly in the areas of biology, zoology, and botany. In all these disciplines, specimens are examined under a microscope.

hope it helps 

8 0

2 years ago

Read 2 more answers

Which statement about the periodic table is true?

dedylja [7]

Answer

Two different elements have similar chemical properties when they have the same number of valence electrons in their outermost energy level. ... Elements in the same column of the Periodic Table have the same number of valence electrons – that's why they have similar chemical properties.

8 0

3 years ago

Ethanol is a common laboratory solvent and has a density of 0.789 g/mL. What is the mass, in grams, of 149 mL of ethanol ?

UNO [17]

Density = mass/volume

If you have the density and volume of a substance, you can use this relationship to calculate the mass. Here, you have 149 milliliters of ethanol, and there are 0.789 grams of ethanol in every milliliter of ethanol. So the mass of 149 mL of ethanol can be obtained by multiplying: (0.789 g/mL)(149 mL) = 118 grams of ethanol.

4 0

3 years ago