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Montano1993 [528]
4 years ago
5

What are variables that do not change in a experiment called

Chemistry
1 answer:
lozanna [386]4 years ago
3 0
Controlled variables: do not change as they must be held constant

Independent variables: are controlled and manipulated

Dependent variables: effected by changes to the independent variable
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I just want to check to see if the answer my child has is right.​
Law Incorporation [45]

Answer:

2= Moles of SO₂ produced from 0.356 moles of PbS = 0.356 mol

3= Mass of hydrogen = 0.45 g

3= Mass of oxygen = 3.616  g

4 = Theoretical yield of P₂O₅ = 14.2 g.

Explanation:

Q2= Given data:

Moles of PbS = 0.356 mol

Moles of PbO = ?

Moles of SO₂ = ?

Solution:

Chemical equation:

2PbS + 3O₂  → 2PbO + 2SO₂

Now we will compare the moles of  PbS with PbO and SO₂ from balanced chemical equation.

                    PbS            :       PbO

                      2               :          2

                       0.356      :          0.356

Moles of PbO produced from 0.356 moles of PbS = 0.356 mol

                       

                  PbS               :       SO₂

                    2                  :         2

                    0.356          :         0.356

Moles of SO₂ produced from 0.356 moles of PbS = 0.356 mol

Q= 3

Given data:

Mass of water = 4.05 g

Mass of hydrogen = ?

Mass of oxygen = ?

Solution:

Chemical equation:

2H₂O   →   2H₂  + O₂

Number of moles of water:

Number of moles of water = mass/ molar mass

Number of moles of water = 4.05 g/ 18 g/mol

Number of moles of water = 0.225 mol

Now we compare the moles of water with hydrogen and oxygen.

                             H₂O            :              H₂

                               2              :                2

                             0.225        :              0.225

Mass of hydrogen:

Mass of hydrogen = moles × molar mass

Mass of hydrogen =  0.225 mol × 2g/mol

Mass of hydrogen = 0.45 g

                              H₂O            :              O₂

                               2              :                1

                             0.225        :              1/2×0.225 = 0.113 mol

Mass of oxygen:

Mass of oxygen = moles × molar mass

Mass of oxygen =  0.113 mol × 32g/mol

Mass of oxygen = 3.616  g

Q 4

Given data:

Mass of phosphorus = 3.07 g

Mass of oxygen = 6.09 g

Theoretical yield of P₂O₅ = ?

Chemical equation:

4P + 5O₂  → 2P₂O₅

Number of moles of phosphorus = mass/ molar mass

Number of moles of phosphorus = 3.07 g/ 31 g/mol

Number of moles of phosphorus = 0.1 mol

Number of moles of oxygen = mass/ molar mass

Number of moles of oxygen = 6.09 g/ 32 g/mol

Number of moles of oxygen = 0.2 mol

Now we will compare the moles of P₂O₅ with oxygen and phosphorus.

             O₂          :        P₂O₅

              5           :           2

             0.2         :          2/5 ×0.2 =  0.08 mol

              P           :        P₂O₅

             4            :           2

            0.1           :           2/4×0.1 = 0.05 mol

The number of moles of P₂O₅ produced from phosphorus are less that's why phosphorus will be limiting reactant.

Mass of P₂O₅ = moles × molar mass

Mass of P₂O₅ = 0.05 mol × 283.88 g/mol

Mass of P₂O₅ = 14.2 g

Theoretical yield of P₂O₅ = 14.2 g.

3 0
3 years ago
When must scientist conduct controlled experiments ?
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Usually when scientist wants to test whether one compound or one phenotype is related to another phenotype. Then they need to control this variable when conducting experiments.
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What is not within the scope of chemistry
ankoles [38]

hello!

your answer will be

The origin of the matter does not usually fall into chemistry

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5 0
4 years ago
Match the time frame listed on the left with the characteristic listed on the
SVEN [57.7K]

mesozoic era - age of the dinosaurs

end of the paleozoic era - most of earth a desert

end of the mesozoic era - a layer of iridium deposited all over earth

5 0
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Learn about personal happiness​
Tju [1.3M]

Answer:

Find out what to do first.

Give yourself a confidence boost.

Fuel your progress by learning how to feel better about yourself.

Create balance and overcome burnout.

Build a growth mindset for happiness.

Make positive memories.

Find those silver linings.

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