<span>The relation between number of half-lives and the amount of sample that remained is expressed as:
(1/2)^n = x
So, given is 7.
To find x, we will change the equation with 7:
(1/2)^n = x
(1/2)^7 = x
0.5^7 = x
0.0078125 = x
0.0078125 x 100% = x
x = 0.78125
Therefore, 0.78 % of a radioactive species would be created as daughter material after seven half-lives.</span>
Answer:
We need 3910.5 joules of energy
Explanation:
Step 1: Data given
Mass of aluminium = 110 grams
Initial temperature = 52.0 °C
Final temperature = 91.5 °C
Specific heat of aluminium = 0.900 J/g°C
Step 2: Calculate energy required
Q = m*c*ΔT
⇒with Q = the energy required = TO BE DETERMINED
⇒with m = the mass of aluminium = 110 grams
⇒with c = the specific heat of aluminium = 0.900 J/g°C
⇒with ΔT = the change in temperature = T2 - T1 = 91.5 °C - 52.0 °C = 39.5 °C
Q = 110 grams * 0.900 J/g°C * 39.5
Q = 3910.5 J
We need 3910.5 joules of energy
If the solvent level in the developing jar is deeper than the origin (spotting line) of the TLC plate, the solvent will dissolve the compounds into the solvent reservoir instead of allowing them to move up the plate by capillary action. Thus, you will not see spots after the plate is developed.
What is Thin Layer Chromatography (TLC)?
- TLC is a simple, quick, and inexpensive procedure that gives the chemist a quick answer as to how many components are in a mixture.
- TLC is also used to support the identity of a compound in a mixture when the Rf of a compound is compared with the Rf of a known compound.
- A TLC plate is a sheet of glass, metal, or plastic which is coated with a thin layer of a solid adsorbent (usually silica or alumina). A small amount of the mixture to be analysed is spotted near the bottom of this plate.
- The TLC plate is then placed in a shallow pool of a solvent in a developing chamber so that only the very bottom of the plate is in the liquid. This liquid, or the eluent, is the mobile phase, and it slowly rises up the TLC plate by capillary action.
- As the solvent moves past the spot that was applied, an equilibrium is established for each component of the mixture between the molecules of that component which are adsorbed on the solid and the molecules which are in solution.
- In principle, the components will differ in solubility and in the strength of their adsorption to the adsorbent and some components will be carried farther up the plate than others. When the solvent has reached the top of the plate, the plate is removed from the developing chamber, dried, and the separated components of the mixture are visualized. If the compounds are coloured, visualization is straightforward.
- Usually the compounds are not coloured, so a UV lamp is used to visualize the plates. The plate itself contains a fluorescent dye which glows everywhere except where an organic compound is on the plate.
To learn more about TLC: brainly.com/question/13483325
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Answer:
There are 0.1 moles of solute in 250 mL of 0.4 M solution.
Explanation:
First, recognize that the molar concentration tells you how many moles of the solute are present in one liter of solution. In a 0.4 M solution, there are 0.4 moles of solute in every liter of solution. You can determine the number of moles of solute in 250 mL of the solution using dimensional analysis.
250
ml . 1L/1000 L . 0.4mol / 1L
Units of liters and milliliters cancel, leaving you with a final answer in units of moles, at 0.1 mol.
Answer:
88.92 grams of Ca(OH)₂ are required
Explanation:
Molarity means mol/L, so 0.6 M are the moles of solute in 1 L of solution.
In 2 L, we 'll have the double of moles, 1.2
Mol . molar mass = grams
1.2 mol . 74.1 g/m = 88.92 grams of solute
