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Grace [21]
4 years ago
8

Jamie is measuring the mass of one mole of carbon. She measures the mass 4 times, achieving the following measurements: 11.86 g,

11.87 g, 11.89 g, and 11.90 g. If the accepted value of one mole of carbon is 12.11 g, how can Jamie's measurements best be described
Chemistry
1 answer:
azamat4 years ago
7 0

This is an incomplete question, here is a complete question.

Distinguish between Accuracy and Precision Question Jamie is measuring the mass of one mole of carbon. She measures the mass 4 times, achieving the following measurements: 11.86 g, 11.87 g, 11.89 g, and 11.90 g. If the accepted value of one mole of carbon is 12.11 g, how can Jamie's measurements best be described?

Select the correct answer below:

Jamie's measurements are both precise and accurate,

Jamie's measurements are accurate but not precise.

Jamie's measurements are precise but not accurate,

Jamie's measurements are neither precise nor accurate,

Answer : The correct option is, Jamie's measurements are precise but not accurate.

Explanation :

Accuracy : It is defined as the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 50 kg and one person weighed 48 kg and another person weighed 55 kg. Then, the weight measured by first person is more accurate.

Precision : It is defined as the closeness of two or more measurements to each other.

For Example: If you weigh a given substance five times and you get 1.8 kg each time. Then the measurement is said to be precise.

Level of precision is determined by the maximum number of decimal places.

As we are given that:

The measurements are, 11.86, 11.87, 11.89 and 11.90

The accepted value is, 12.11

The average of these values =  \frac{11.86+11.87+11.89+11.90}{4}=11.88

From this we conclude that, these measurements are close to each other that means they are precise. But the accepted value are not equal to average of four values that means they are not accurate.

Hence, the correct option is, Jamie's measurements are precise but not accurate.

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Identify the limiting reactant in the reaction of nitrogen and hydrogen to form NH3 if 5.23 g of N2 and 5.52 g of H2 are combine
Marrrta [24]

Answer:

1) The limiting reactant is N₂ because it is present with the lower no. of moles than H₂.

2) The amount (in grams) of excess reactant H₂ = 4.39 g.

Explanation:

  • Firstly, we should write the balanced equation of the reaction:

<em>N₂ + 3H₂ → 2NH₃.</em>

<em>1) To determine the limiting reactant of the reaction:</em>

  • From the stichiometry of the balanced equation, 1.0 mole of N₂ reacts with 3.0 moles of H₂ to produce 2.0 moles of NH₃.
  • This means that <em>N₂ reacts with H₂ with a ratio of (1:3).</em>
  • We need to calculate the no. of moles (n) of N₂ (5.23 g) and H₂ (5.52 g) using the relation:<em> n = mass / molar mass.</em>

The no. of moles of N₂ in (5.23 g) = mass / molar mass = (5.23 g) / (28.00 g/mol) = 0.1868 mol.

The no. of moles of H₂ (5.52 g) = mass / molar mass = (5.52 g) / (2.015 g/mol) = 2.74 mol.

  • From the stichiometry, N₂ reacts with H₂ with a ratio of (1:3).

The ratio of the reactants of N₂ (5.23 g, 0.1868 mol) to H₂ (5.52 g, 2.74 mol) is (1:14.67).

∴ The limiting reactant is N₂ because it is present with the lower no. of moles than H₂.

0.1868 mol of N₂ react completely with 0.5604 mol of H₂ and the remaining of H₂ is in excess.

<em>2) To determine the amount (in grams) of excess reactant of the reaction:</em>

  • As showed in the part 1, The limiting reactant is N₂ because it is present with the lower no. of moles than H₂.
  • Also, 0.1868 mol of N₂ react completely with 0.5604 mol of H₂ and the remaining of H₂ is in excess.
  • The no. of moles are in excess of H₂ = 2.74 mol - 0.5604 mol (reacted with N₂) = 2.1796 mol.
  • ∴ The amount (in grams) of excess reactant H₂ = n (excess moles) x molar mass = (2.1796 mol)((2.015 g/mol) = 4.39 g.

4 0
3 years ago
As a technician in a large pharmaceutical research firm, you need to produce 300. mL of 1.00 M a phosphate buffer solution of pH
tamaranim1 [39]

Answer:  pH = 7.36. The pKa of H2PO4− is 7.21.

Explanation:

4 0
3 years ago
Problem PageQuestion A chemist makes of magnesium fluoride working solution by adding distilled water to of a stock solution of
igomit [66]

Answer:

5.37 × 10⁻⁴ mol/L

Explanation:

<em>A chemist makes 660. mL of magnesium fluoride working solution by adding distilled water to 230. mL of a 0.00154 mol/L stock solution of magnesium fluoride in water. Calculate the concentration of the chemist's working solution. Round your answer to 3 significant digits.</em>

Step 1: Given data

  • Initial concentration (C₁): 0.00154 mol/L
  • Initial volume (V₁): 230. mL
  • Final concentration (C₂): ?
  • Final volume (V₂): 660. mL

Step 2: Calculate the concentration of the final solution

We want to prepare a dilute solution from a concentrated one. We can calculate the concentration of the final solution using the dilution rule.

C₁ × V₁ = C₂ × V₂

C₂ = C₁ × V₁ / V₂

C₂ = 0.00154 mol/L × 230. mL / 660. mL = 5.37 × 10⁻⁴ mol/L

5 0
3 years ago
A bottle of 2 moles of an ideal diatomic gas experiences a temperature increase of 50.0K at constant volume. (a) Find the increa
andre [41]

Answer:

Explanation:

a) For diatomic gas: Translational motion = 3 and rotational motion = 2

∴ Total (internal energy) = 3 + 2 = 5

b) Translational + Rotational + Vibrational = 3 + 2 + 1 = 6

c) Linear molecule  

i) Non linear molecule

ii)  Monatomic molecule

5 0
3 years ago
A 0.1 gram sample of an unknown liquid is vaporized completely at 70 degrees C to fill a 750mL flask. The pressure is 0.05951atm
Deffense [45]

Answer:

The molar mass of the liquid 62.89 g/mol

Explanation:

Step 1: Data given

Mass of the sample = 0.1 grams

Temperature = 70°C

Volume = 750 mL

Pressure = 0.05951 atm

Step 2: Calculate the number of moles

p*V = n*R*T

n = (p*V)/(R*T)

⇒ with n = the number of moles gas = TO BE DETERMINED

⇒ with p = The pressure = 0.05951 atm

⇒ with V = The volume of the flask = 750 mL = 0.750 L

⇒ with R = The gasconstant = 0.08206 L*atm/K*mol

⇒with T = the temperature = 70 °C = 343 Kelvin

n = (0.05951 *0.750)/(0.08206*343)

n = 0.00159 moles

Step 3: Calculate molar mass

Molar mass = mass / moles

Molar mass =0.1 gram /  0.00159 moles

Molar mass = 62.89 g/mol

The molar mass of the liquid 62.89 g/mol

6 0
3 years ago
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