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3 years ago

14

Complete each of the definitions with the appropriate phrase. Precision means that ___measurements are close to_

___ Accuracy means that___________ measurements are close to_____________

1 answer:

Gwar [14]3 years ago

5 0

Answer:

Precision means that <u><em>independent </em></u>measurements are close to <u><em>each other.</em></u>

Accuracy means that <u><em>independent</em></u> measurements are close to <u><em>a known or accepted value.</em></u>

Explanation:

Accuracy refers to how close the measurements of a measurement system are to the true value while precision refers to how close the measurements are to each other. In other words, accuracy is the closeness of the value of one or more independent measurements to a true value, and precision is the closeness of two or more values of several measurements to each other.

Both are independent of each other, that is to say that the results in the values of a measurement can be precise and not exact, and vice versa.

So:

Precision means that <u><em>independent </em></u>measurements are close to <u><em>each other.</em></u>

Accuracy means that <u><em>independent</em></u> measurements are close to <u><em>a known or accepted value.</em></u>

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What do all four of these types of molecules have in common?

nalin [4]

D. They all contain carbon as an important part of their structure.

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3 years ago

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.8

Lubov Fominskaja [6]

Complete Question

You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.82 when exactly 13 mL of base had been added, you notice that the concentration of the unknown acid was 0.1 M. What is the pKa of your unknown acid?

Answer:

The pK_a value is $pK_a =7.82$

Explanation:

From the question we are told

The volume of base is $V_B = 26.mL = 0.0260L$

The pH of solution is $pH = 7.82$

The concentration of the acid is $C_A = 0.1M$

From the pH we can see that the titration is between a strong base and a weak acid

Let assume that the the volume of acid is $V_A = 18mL= 0.018L$

Generally the concentration of base

$C_B = \frac{C_AV_A}{C_B}$

Substituting value

$C_B = \frac{0.1 * 0.01800}{0.0260}$

$C_B= 0.0692M$

When 13mL of the base is added a buffer is formed

The chemical equation of the reaction is

$HA_{(aq)} + OH^-_{(aq)} --------> A^{+}_{(aq)} + H_2 O_{(l)}$

Now before the reaction the number of mole of base is

$No \ of \ moles[N_B] = C_B * V_B$

Substituting value

$N_B = 0.01300 * 0.0692$

$= 0.0009 \ moles$

Now before the reaction the number of mole of acid is

$No \ of \ moles = C_B * V_B$

Substituting value

$N_A = 0.01800 *0.1$

$= 0.001800 \ moles$

Now after the reaction the number of moles of base is zero i.e has been used up

this mathematically represented as

$N_B ' = N_B - N_B = 0$

The number of moles of acid is

$N_A ' = N_A - N_B$

$= 0.0009\ moles$

The pH of this reaction can be mathematically represented as

$pH = pK_a + log \frac{[base]}{[acid]}$

Substituting values

$7.82 = pK_a +log \frac{0.0009}{0.0009}$

$pK_a =7.82$

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3 years ago

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Korvikt [17]

Answer:

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3 years ago

What is the mass of aluminum oxide (101.96 g/mol) produced from 1.74 g of manganese(iv) oxide (86.94 g/mol)?

NemiM [27]

the mass of aluminum oxide (101.96 g/mol) produced from 1.74 g of manganese(iv) oxide (86.94 g/mol) is 1.36g

The reaction is 3 MnO2 + 4 Al ------ 2Al2o3+ Mn

3 mole of manganese oxide give 2 moles of aluminum oxide so by the reaction n( MnO2)/3 =n(al203)2

the formula is n= mass/M so, now substituting values

m (Al2O3)= m(MnO2) X 2 X M (Al2O3) / M(MnO2 X3

so, by substituting values, 2 X101.96 X1.74g / 3 X 86.94 =1.36g

so mass of aluminum oxide obtained = 1.36g

To learn more about Mass:

brainly.com/question/19694949

#SPJ4

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2 years ago

Which term describes a chemical equation in which all highly soluble compounds are written as dissociated ions

BartSMP [9]

Answer: IONIC EQUATION.

Explanation:

A chemical equation is defined as the form by which a chemical reaction is represented mathematically. These are written in the form of symbols and chemical formulas of reactants and products which are taking part in the chemical reaction. A chemical equation can be written in two forms, these include:

--> MOLECULAR EQUATION: in this type of equations, the compounds are written and represented in a molecular form. This is sometimes referred to as a balanced equation.

--> IONIC EQUATION: This is a type of chemical equation in which the electrolytes in aqueous solution are expressed as dissociated ions. A typical illustrated example is seen in the reaction between AgNO3(aq) and NaCl(aq) :

Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) → AgCl(s) + Na+(aq) + NO3-(aq)

The (aq) written in the above equation signifies they are in aqueous solution.

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