16. What is a pure substance formed when two or more different elementscombine called?A. compoundB. moleculeC. element
1 answer:
<h2>Answer:</h2>
Compound. Option A is correct
<h2>Explanations:</h2>
When two or more different elements combines, a compound is formed. For instance, if carbon and oxygen combines, carbondioxide is formed according to the equation;
From the reaction, carbon and oxygen are the elements while carbondioxide is the compound. Hence we can conclude that a pure substance formed when two or more different elements combine called compound.
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Let us first calculate the accepted value of sulfate using the molar mass of sodium sulfate.
The molar mass of sodium sulfate is 2 Na + S + 4 O = 2 (22.99) + 32.07 + 4 (16)
Molar mass of Sodium sulfate = 142.05
Molar mass of sulfate = S + 4 (O) = 32.07 + 4 (16) = 96.07
% of sulfate in sodium sulfate = (Molar mass of SO4 / Molar mass of Na2SO4) x 100
% of sulfate = (96.07/142.05) x 100
% of sulfate = 67.6%
Theoretical value for % Sulfate is 67.6%
Percent error is calculated as
Percent Error =
Let us calculate mean for student A.
Mean for student A = (68.6 + 66.2 + 67.1) / 3 = 201.9/3 = 67.3 %
% error for student A =
% error for student A = 0.44%
Mean for student B = (66.7 +66.6 + 66.5)/3 = 199.8 /3 = 66.6 %
% error for student B =
% error for student B = 1.48%
Accuracy is the closeness of experimental values to the true value. This is defined in terms of absolute and percent errors.
Since percent error for student A is lower, we can say that student A was more accurate.
The precision of the data depends on the closeness of experimental values to each other. We can see that experimental values for student B were close to each other.
Therefore we can say that student B was more precise.