What is the purpose of an experiment as a part of the scientific method

A Series of choices between two characteristics that is used to identify an organism is called a

Zielflug [23.3K]

Answer: Dichotomous

Using a Dichotomous Key to Identify Organisms

A dichotomous key is a tool used by biologists to identify organisms in a group through a process of answering yes or no questions about the organism. Dichotomous means 'divided into two parts', as each question about an organism has two choices.

8 0

4 years ago

You find a little bit (0.150g) of a chemical marked Tri-Nitro-Toluene. Upon complete combustion in oxygen, you collect 0.204 g o

Elan Coil [88]

Answer:

The empirical formula is C7H5N3O6

Explanation:

Step 1: Data given

Mass of sample = 0.150 grams

Mass of CO2 = 0.204 grams

Molar mass CO2 = 44.01 g/mol

Mass of H2O = 0.030 grams

Molar mass H2O = 18.02 g/mol

Molar mass C = 12.01 g/mol

Molar mass H = 1.01 g/mol

Molar mass O = 16.0 g/mol

Step 2: Calculate moles CO2

Moles CO2 = mass CO2 / molar mass CO2

Moles CO2 = 0.204 grams / 44.01 g/mol

Moles CO2 = 0.00464 moles

Step 3: Calculate moles C

For 1 mol CO2 we have 1 mol C

For 0.00464 moles we have 0.00464 moles C

Step 4: Calculate mass C

Mass C = 0.00464 moles * 12.01 g/mol

Mass C = 0.0557 grams

Step 5: Calculate moles H2O

Moles H2O = 0.030 grams / 18.02 g/mol

Moles H2O = 0.00166 moles

Step 6: Calculate moles H

For 1 mol H2O we have 2 moles H

For 0.00166 moles H2O we have 2* 0.00166 = 0.00332 moles H

Step 7: Calculate mass H

Mass H = 0.00332 moles * 1.01 g/mol

Mass H = 0.00335 grams

Step 8: Calculate mass N

Mass N = 0.185 * 0.150 grams

Mass N = 0.02775 grams

Step 9: Calculate moles N

Moles N = 0.02775 grams / 14.0 g/mol

Moles N = 0.00198 moles

Step 10: Calculate mass O

Mass O = 0.150 grams - 0.02775 - 0.00335 - 0.0557

Mass O = 0.0632 grams

Step 11: Calculate moles O

Moles O = 0.0632 grams / 16.0 g/mol

Moles O = 0.00395 moles

Step 11: Calculate mol ratio

We divide by the smallest amount of moles

C: 0.00464 moles / 0.00198 moles =2.33

H: 0.00332 moles / 0.00198 moles = 1.66

N: 0.00198 moles / 0.00198 moles = 1

O: 0.00395 moles / 0.00198 moles = 2

For 1 mol N we have 2.33 moles C, 1.66 moles H and 2 moles O

OR

For 3 moles N we have 7 moles C, 5 moles H and 6 moles O

The empirical formula is C7H5N3O6

5 0

3 years ago

The extraction of aluminum metal from the aluminum hydroxide found in bauxite by the Hall-Héroult process is one of the most rem

son4ous [18]

Answer:

10 kg Al(OH)₃

Explanation:

There is some info missing. I think this is the original question.

<em>The extraction of aluminum metal from the aluminum hydroxide found in bauxite by the Hall-Héroult process is one of the most remarkable success stories of 19th-century chemistry, turning aluminum from a rare and precious metal into the cheap commodity it is today. </em>

<em>In the first step, aluminum hydroxide reacts to form alumina (Al₂O₃) and water: 2 Al(OH)₃(s) → Al₂O₃(s) + 3H₂O(g). In the second step, alumina (Al₂O₃ and carbon react to form aluminum and carbon dioxide: 2Al₂O₃(s)+3C(s)→4Al(s)+3CO₂(g). Suppose the yield of the first step is 63% and the yield of the second step is 89%. </em>

<em>Calculate the mass of aluminum hydroxide required to make 2.0 kg of aluminum. Be sure your answer has a unit symbol, if needed, and is rounded to the correct number of significant digits.</em>

<em />

Let's consider the 2 steps in the synthesis of Al.

Step 1: 2 Al(OH)₃(s) → Al₂O₃(s) + 3 H₂O(g)

Step 2: 2 Al₂O₃(s) + 3 C(s) → 4 Al(s) + 3 CO₂(g)

In Step 2, the percent yield of Al is 89% and the real yield is 2.0 kg. The theoretical yield is:

2.0 kg (R) × (100 kg (T) / 89 kg (R)) = 2.2 kg = 2.2 × 10³ g

In Step 2, the mass of Al is 4 × 26.98 g = 107.9 g and the mass of Al₂O₃ is 2 × 101.96 g = 203.92g. The mass of Al₂O₃ that produced 2.2 × 10³ g of Al is:

2.2 × 10³ g Al × (203.92g Al₂O₃ / 107.9 g Al) = 4.2 × 10³ g Al₂O₃

In Step 1, the percent yield of Al₂O₃ is 63% and the real yield is 4.2 × 10³ g. The theoretical yield is:

4.2 × 10³ g (R) × (100 g (T)/ 63 g (R)) = 6.7 × 10³ g

In Step 1, the mass of Al₂O₃ is 101.96 g and the mass of Al(OH)₃ is 2 × 78.00 g = 156.0 g. The mass of Al(OH)₃ that produced 6.7 × 10³ g of Al₂O₃ is:

6.7 × 10³ g Al₂O₃ × (156.0 g Al(OH)₃ / 101.96 g Al₂O₃) = 1.0 × 10⁴ g Al(OH)₃ = 10 kg Al(OH)₃

7 0

4 years ago

Which best describes why a liquid needs a container when a solid does not?Solids fill their containers, and liquids have definit

Rina8888 [55]

The correct answer choice which best describes why a liquid needs a container when a solid does not is simply because:

Solids have definite shapes, and liquids fill their containers.

Matter is classified as element, compounds and mixtures

<h3>What is an element?</h3>

An element is a substance which cannot be split into simpler forms by an ordinary chemical process. This simply goes to say that elements are substances which cannot be decomposed into simpler substances by ordinary chemical reactions.

An atom is the smallest unit or part of an element which can take part in a chemical reaction.

On a general note, elements are classified as thus:

Metals, non-metal, and metalloid.

The extreme left side elements in the periodic table are metals, for example, aluminum, sodium, calcium, caesium, etc.

However, elements on the right side are generally referred to as non-metals, carbon, chlorine, oxygen,

So therefore, the correct answer choice which best describes why a liquid needs a container when a solid does not is simply because:

Solids have definite shapes, and liquids fill their containers.

Learn more about atoms and elements:

brainly.com/question/6258301

#SPJ1

5 0

2 years ago

The elements listed in the periodic table account

ddd [48]

Answer:

Only 4 %

Explanation:

Just about 4 percent of the known universe overall mass consists of atomic nuclei and is therefore described by chemical components. This proportion is around 15 percent of the total mass, with dark energy becoming the majority of the material .

3 0

3 years ago