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Marizza181 [45]
3 years ago
15

By making several measurements with the same balance, a chemist obtained values of 5.224 g, 5.235 g, and 5.259 g for the mass of

a sample. Without knowing the actual mass of the sample, we can tell that these measurements have .
a) good precision
b) good accuracy
c) poor precision
d) poor accuracy
Chemistry
1 answer:
stepan [7]3 years ago
6 0

Answer:

a) Measurements have a good precision.

Explanation:

Accuracy is the proximity of the data to the value considered as real, in this situation we do not know the real value and we do not know if the data is accurate or not, so we can discard options b and d.

Now, precision is the proximity of the data obtained among themselves and that is what we can observe, so the appropriate answer is the option a.

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The moon, man has not been to mars yet
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A welding torch produces a flame by burning acetylene fuel in the presence of oxygen. This flame is used to melt a metal. Which
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Answer:

chemical energy into thermal energy

Explanation:

The reaction taking place is as follows

2C₂H₂ + 5O₂ = 4CO₂ + 2H₂O + Heat

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Thus we can say that in the whole process , chemical energy is converted into heat energy .

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2 years ago
Which methods will help you properly identify pH with indicator paper? Check all that apply. Set a piece of pH paper in front of
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Set a piece of pH paper in front of each solution before testing to keep organized.

Use a transfer pipet to remove a few drops from the solution to drop onto the paper.

Wait a minute or so before reading color.

Is the correct answer...

4 0
3 years ago
Read 2 more answers
A balloon filled with helium gas at 1.00 atm occupies 12.9 L. What volume would the balloon occupy in the upper atmosphere, at a
Taya2010 [7]

Answer:

67,9 L

Explanation:

Boyle's Law indicates that the pressure of a fixed amount of gas at a constant temperature is inversely proportional to the volume of a gas, for a constant amount of gas we can write:

P1V1=P2V2

For the problem:

P1= 1 atm, V1= 12,9 L

P2=0,19 atm, V2=?

Therefore:

V2=P1V1/P2.................... V2=1 atm*12,9L/0,19 atm = 67,9 L

The balloon would occupy a volume of 67,9 L in the upper atmosphere.

5 0
3 years ago
If the K a Ka of a monoprotic weak acid is 7.3 × 10 − 6 , 7.3×10−6, what is the pH pH of a 0.40 M 0.40 M solution of this acid?
olga_2 [115]

Answer:

pH =3.8

Explanation:

Lets call the monoprotic weak acid HA, the dissociation equilibria in water will be:

HA + H₂O   ⇄ H₃O⁺ + A⁻    with  Ka = [ H₃O⁺] x [A⁻]/ [HA]

The pH is the negative log of the H₃O⁺ concentration, we know the equilibrium constant, Ka and the original acid concentration. So we will need to find the [H₃O⁺] to solve this question.

In order to do that lets set up the ICE table helper which accounts for the species at equilibrium:

                          HA                                   H₃O⁺                          A⁻          

Initial, M             0.40                                   0                              0

Change , M          -x                                     +x                            +x

Equilibrium, M    0.40 - x                              x                               x

Lets express these concentrations in terms of the equilibrium constant:

Ka = x² / (0.40 - x )

Now the equilibrium constant is so small ( very little dissociation of HA ) that is safe to approximate 0.40 - x to 0.40,

7.3 x 10⁻⁶ = x² / 0.40  ⇒ x = √( 7.3 x 10⁻⁶ x 0.40 ) = 1.71 x 10⁻³

[H₃O⁺] = 1.71 x 10⁻³

Indeed 1.71 x 10⁻³ is small compared to 0.40 (0.4 %). To be a good approximation our value should be less or equal to 5 %.

pH = - log ( 1.71 x 10⁻³ ) = 3.8

Note: when the aprroximation is greater than 5 % we will need to solve the resulting quadratic equation.

4 0
3 years ago
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