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lions [1.4K]
3 years ago
11

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 13.0 g of luminol into a total vol

ume of 75.0 mL of H2O. What is the molarity of the stock solution of luminol?
Chemistry
1 answer:
Andrews [41]3 years ago
3 0

Answer:

0.978 M

Explanation:

Given data

  • Mass of luminol (solute): 13.0 g
  • Volume of the solution = volume of water: 75.0 mL = 0.0750 L

We can find the molarity of the stock solution of luminol using the following expression.

M = mass of solute / molar mass of solute × liters of solution

M = 13.0 g / 177.16 g/mol × 0.0750 L

M = 0.978 M

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HELP.
Kamila [148]

Answer:

The mass of tin is 164 grams

Explanation:

Step 1: Data given

Specific heat heat of tin = 0.222 J/g°C

The initial temeprature of tin = 80.0 °C

Mass of water = 100.0 grams

The specific heat of water = 4.184 J/g°C

Initial temperature = 30.0 °C

The final temperature = 34.0 °C

Step 2: Calculate the mass of tin

Heat lost = heat gained

Qlost = -Qgained

Qtin = -Qwater

Q = m*c*ΔT

m(tin)*c(tin)*ΔT(tin) = -m(water)*c(water)*ΔT(water)

⇒with m(tin) = the mass of tin = TO BE DETERMINED

⇒with c(tin) = the specific heat of tin = 0.222J/g°C

⇒with ΔT(tin) = the change of temperature of tin = T2 - T1 = 34.0°C - 80.0°C = -46.0°C

⇒with m(water) = the mass of water = 100.0 grams

⇒with c(water) = the specific heat of water = 4.184 J/g°C

⇒with ΔT(water) = the change of temperature of water = T2 - T1 = 34.0° C - 30.0 °C = 4.0 °C

m(tin) * 0.222 J/g°C * -46.0 °C = -100.0g* 4.184 J/g°C * 4.0 °C

m(tin) =  163.9 grams ≈ 164 grams

The mass of tin is 164 grams

4 0
3 years ago
The longer the reaction time is, the the reaction rate is. Reaction time is to reaction rate.
Nostrana [21]

Answer:

False.

Explanation:

Rate of reaction  also depends on the number of collision that is being happening in reacting molecules. So concentration of the reactants is also important to decide the rate of reaction.

The rate of reaction is dependent on the concentration as well.

As the concentration of reactants decreases with time number of collisions also decreases .

6 0
3 years ago
Read 2 more answers
What is the change in atomic number when an atom emits a beta particle?
salantis [7]

When an atom emits a beta particle from the nucleus, the nucleus only has one more proton and one less neutron and this will make the atomic mass number remains unchanged while the atomic number increases by 1.

<span>I hope this answer helps you!</span>

4 0
3 years ago
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The electron affinity of Bi is -94.6 kJ and the value for At is -280 kJ. What is the approximate electron affinity for Po?
lys-0071 [83]

Answer:

48 KJ mol-1

Explanation:

3 0
3 years ago
Which two particles in an atom are equal in mass
Taya2010 [7]
Protons and neutrons.

Note: They probably are ABOUT the same mass. Don't think they are exactly the same.

Hope this helps! 
8 0
3 years ago
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