1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
EastWind [94]
3 years ago
13

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 18.0 g of luminol into a total vol

ume of 75.0 mL of H2O. What is the molarity of the stock solution of luminol? Express your answer with the appropriate units.
Chemistry
1 answer:
Paladinen [302]3 years ago
3 0

Answer:

1.36M

Explanation:

Luminol is a compound having the molecular formula as C8H7N3O2.

To know the molarity of the stock solution of Luminol, we shall carry out the following:

Step 1:

we shall calculate the number of mole in 18g of luminol. This is shown below:

Molar mass of C8H7N3O2 = (12x8) + (7x1 ) + (14x3) + (16x2)

= 96 + 7 + 42 + 32

= 177g/mol

Mass of C8H7N3O2 = 18g

Number of mole of C8H7N3O2 =..?

Mole = Mass /Molar Mass

Number of mole of C8H7N3O2 = 18/177 = 0.102 mole.

Step 2:

Conversion of 75.0 mL of H2O to Litre (L).

1000mL = 1L

Therefore, 75mL = 75/1000 = 0.075L

Step 3:

Determination of the molarity of the stock solution of Luminol.

Molarity is simply defined as the mole of solute per unit litre of water. Mathematically, it is represented as:

Molarity = mole /Volume

With the above formula, we can obtain the molarity of the stock solution of Luminol as follow:

Mole of C8H7N3O2 = 0.102 mole

Volume of water = 0.075L

Molarity =..?

Molarity = mole /Volume

Molarity = 0.102/0.075

Molarity = 1.36M

Therefore, the molarity of the stock solution of Luminol is 1.36M.

You might be interested in
A substance is found to consist of 1.900g of silver, 0.250g of nitrogen, and 0.850g of oxygen. what is the percent by mass of ox
Galina-37 [17]
The  percentage  by mass  of  oxygen  in  the  compound

find  the total  mass=(  1.900+  0250 +0.850) =  3
the  percentage  mass  mass of  oxgyen/total  mass  x100

that  is  (0.850/3)  x100=28.33%
7 0
3 years ago
What happens if a cell cannot do cellular respiration?
Dahasolnce [82]

Answer:

the cell enentually dies because it has no way to survive

Explanation:

8 0
3 years ago
Consider the following reaction:
iren [92.7K]

Answer:

A. ΔG° = 132.5 kJ

B. ΔG° = 13.69 kJ

C. ΔG° = -58.59 kJ

Explanation:

Let's consider the following reaction.

CaCO₃(s) → CaO(s) + CO₂(g)

We can calculate the standard enthalpy of the reaction (ΔH°) using the following expression.

ΔH° = ∑np . ΔH°f(p) - ∑nr . ΔH°f(r)

where,

n: moles

ΔH°f: standard enthalpy of formation

ΔH° = 1 mol × ΔH°f(CaO(s)) + 1 mol × ΔH°f(CO₂(g)) - 1 mol × ΔH°f(CaCO₃(s))

ΔH° = 1 mol × (-635.1 kJ/mol) + 1 mol × (-393.5 kJ/mol) - 1 mol × (-1206.9 kJ/mol)

ΔH° = 178.3 kJ

We can calculate the standard entropy of the reaction (ΔS°) using the following expression.

ΔS° = ∑np . S°p - ∑nr . S°r

where,

S: standard entropy

ΔS° = 1 mol × S°(CaO(s)) + 1 mol × S°(CO₂(g)) - 1 mol × S°(CaCO₃(s))

ΔS° = 1 mol × (39.75 J/K.mol) + 1 mol × (213.74 J/K.mol) - 1 mol × (92.9 J/K.mol)

ΔS° = 160.6 J/K. = 0.1606 kJ/K.

We can calculate the standard Gibbs free energy of the reaction (ΔG°) using the following expression.

ΔG° = ΔH° - T.ΔS°

where,

T: absolute temperature

<h3>A. 285 K</h3>

ΔG° = ΔH° - T.ΔS°

ΔG° = 178.3 kJ - 285K × 0.1606 kJ/K = 132.5 kJ

<h3>B. 1025 K</h3>

ΔG° = ΔH° - T.ΔS°

ΔG° = 178.3 kJ - 1025K × 0.1606 kJ/K = 13.69 kJ

<h3>C. 1475 K</h3>

ΔG° = ΔH° - T.ΔS°

ΔG° = 178.3 kJ - 1475K × 0.1606 kJ/K = -58.59 kJ

5 0
3 years ago
Atoms of elements at the top of a group on the periodic table are smaller than the atoms of elements at the bottom of the group.
boyakko [2]

Answer:

Explanation:

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also  decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.  

On left side of periodic table atoms of metals are more reactive by loosing the electrons or we can say metals are more reactive by loosing the electrons so their reactivity increase down the group because of easily  removal of electrons.

On right side of periodic table atoms of nonmetals are more reactive by gaining the electrons. As we move down the group nuclear attraction becomes smaller because of shielding thus electron are less attracted by nucleus and reactivity decreases.

7 0
3 years ago
A tank of gas is found to exert 8.6 atm at 38°C. What would be the required
Vesna [10]

Answer:

36.2 K

Explanation:

Step 1: Given data

  • Initial pressure of the gas (P₁): 8.6 atm
  • Initial temperature of the gas (T₁): 38°C
  • Final pressure of the gas (P₂): 1.0 atm (standard pressure)
  • Final temperature of the gas (T₂): ?

Step 2: Convert T₁ to Kelvin

We will use the following expression.

K = °C +273.15

K = 38 °C +273.15 = 311 K

Step 3: Calculate T₂

We will use Gay Lussac's law.

P₁/T₁ = P₂/T₂

T₂ = P₂ × T₁/P₁

T₂ = 1.0 atm × 311 K/8.6 atm = 36.2 K

6 0
2 years ago
Other questions:
  • The concentration of sugar in a soft drink is measured to be 10.5%. how many grams of sugar are in 125 g of the drink?
    7·1 answer
  • A metabolic pathway that ___ (oxidizes or reduces) an energy-rich source to produce ATP from ADP. Electrons are transferred from
    5·2 answers
  • How does heat flow? Use the following keywords: heat, thermal energy, transfer, same, hot to cold, kinetic energy
    6·1 answer
  • If you examined the human body on a chemical composition basis, which of the following combinations of elements would be most co
    9·1 answer
  • What the mass of a 1.00cm3 piece of iron having a density of 7.90g/cm3
    12·1 answer
  • What is the correct name of a compound that is formed by Si and O​
    12·1 answer
  • the reaction below shows a system in equilibrium how would an increase in the concentration of chemicals affect this reaction?
    9·1 answer
  • Which statement explains the method to adjust the strength of the flame on the Bunsen burner?
    12·1 answer
  • How many carbons atoms are in propane?
    8·2 answers
  • How can you change a objects state of matter
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!