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GenaCL600
6 days ago
6

If you had a 5 gram sample of lawrencium how much would still remain in 30 minutes

Chemistry
1 answer:
VMariaS [2.8K]6 days ago
8 0
There are eight isotopes of lawrencium, and each one is radioactive. I will perform calculations for ²⁶²Lr, which has a half-life of 3.6 hours. Let A₀ denote the initial quantity of lawrencium. The remaining amount after one half-life is ½A₀. After two half-lives, the quantity left is ½ × ½A₀ = (½)²A₀. After three half-lives, the remaining amount is ½ × (½)²A₀ = (½)³A₀, and this pattern continues. We can generalize the formula for the amount remaining: A = A₀(½)ⁿ, where n indicates the number of half-lives. Data: A₀ = 5 g,  t = 30 min. Calculations: (a) Convert the half-life to minutes. (b) Compute n. (c) Determine A.
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How many significant figures in 8400
castortr0y [2913]
The number 8400 has two significant figures.
5 0
23 days ago
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Draw a lewis structure for hccl3. Show all unshared pairs and the formal charges
eduard [2645]

Explanation:

Lewis-dot structure: It illustrates how the atoms in a molecule are bonded together and indicates the presence of unpaired electrons in the molecule.

The molecule in question is, HCCl_3

Carbon possesses '4' valence electrons, hydrogen has '1' valence electron, and chlorine contains '7' valence electrons.

Consequently, the cumulative count of valence electrons in HCCl_3 = 1(1) + 1(4) + 3(7) = 26

Based on the electron-dot structure, there are 8 bonding electrons and 18 non-bonding electrons.

The electron-dot representation for HCCl_3 is depicted below.

Next, we need to assess the formal charges on carbon, hydrogen, and chlorine.

The formula for calculating formal charge:

\text{Formal charge}=\text{Valence electrons}-\text{Non-bonding electrons}-\frac{\text{Bonding electrons}}{2}

\text{Formal charge on carbon}=4-0-\frac{8}{2}=0

\text{Formal charge on hydrogen}=1-0-\frac{2}{2}=0

\text{Formal charge on chlorine}=7-0-\frac{2}{2}=0

6 0
7 days ago
Help on part "c": The forensic technician at a crime scene has just prepared a luminol stock solution by adding 19.0g of luminol
lions [2782]

1. The luminol stock solution has a molarity of 1.431 M.

2. In 2.00 L of the diluted spray, there are 0.12 moles of luminol.

3. The volume of the stock solution from Part A that contains the same number of moles present in the diluted solution from Part B is 83.86 ml.

Additional Information

Stoichiometry in Chemistry focuses on the quantitative aspects of chemical reactions, which includes calculations related to volume, mass, and the count of ions, molecules, and elements.

Key concepts in stoichiometry include:

  • 1. Relative atomic mass
  • 2. Relative molecular mass

This refers to the relative atomic mass of a molecule.

  • 3. Mole

A mole represents the number of particles in a substance equivalent to the number of atoms in 12 grams of carbon-12.

1 mole = 6.02 × 10²³ particles.

The quantity of moles can also be derived by dividing mass (in grams) by either the relative mass of an element or the relative mass of a molecule.

\large{\boxed{\bold{mol\:=\:\frac{grams}{ relative\:mass} }}}

Luminol (C₈H₇N₃O₂) is utilized for detecting blood traces at crime scenes, due to its reaction with iron found in blood.

To prepare a luminol stock solution, 19.0 g of luminol is mixed into a total volume of 75.0 mL of water.

Thus, the molarity is calculated as:

  • 1. Moles of Luminol

- the relative molecular mass of Luminol:

= 8.C + 7.H + 3.N + 2.16

= 8.12 + 7.1 + 3.14 + 2.16

= 177 grams/mol.

Thus, we have:

moles = grams / relative molecular mass.

mole=\frac{19}{177}

moles = 0.1073.

2. Molarity (M)

M = moles / volume

M\:=\:{\frac{ 0.1703 }{75.10^{-3} L}

M = 1.431.

  • b. The concentration of luminol in the spray bottle is 6.00 × 10⁻² M. Therefore, in a 2 L solution, the number of moles is:

moles = M × volume

moles = 6 × 10⁻² × 2

moles = 0.12.

  • c. The molarity of the stock solution (Part A) is 1.431 M.

The diluted solution (Part B) contains 0.12 moles of luminol.

To find the volume of the stock solution (Part A) that has the same moles as the diluted solution (Part B):

volume = moles / M

volume\:=\:\frac{0.12}{1.431}

volume = 0.08386 L = 83.86 mL.

Further Learning

moles of water you can generate

the amount of each atom in the chemical's formula

the proportion of hydrogen to oxygen atoms in 2 L of water

Keywords: mole, volume, molarity, Luminol, relative molecular mass

6 0
1 month ago
Read 2 more answers
The equilibrium constant for the reaction sr(s) + mg2+(aq) ⇌ sr2+(aq) + mg(s) is 2.69 × 1012 at 25°c. calculate e o for a cell m
eduard [2645]
Sr(s)+Mg²+(aq)→Sr²+(aq)+Mg(s)
Number of electrons transferred, n=2. Equilibrium constant,
K=2.69×10∧12
ΔG=-2.303RT logK
R=gas constant=8.314J/mol-k
T= temperature in K= 25°C=25+273=298K
Calculating gives us ΔG = -70922.3J. However, ΔG = -nFE
n= number of electrons transferred in the reaction =2
F= faraday = 96500C
E=cell potential is what?
∴E = ΔG.nF
=-(-70922.3)/2×96500)
=0.367V.
8 0
20 days ago
Two samples of matter differ in temperature by 20°C. What is the difference in temperature of these two samples using the Kelvin
Tems11 [2631]

Answer:

The temperature difference is 293.15 Kelvin.

Explanation:

The provided information:

The temperature difference between the two matters is 20°C

We need to determine this difference in Kelvin =?

To solve this;

Using the formula:

0°C +273.15

Now substituting the values in place of 0.

20°C + 273.15 = 293.15 K

Hence, the temperature differential between the two samples is 293.15 K.

5 0
22 days ago
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