Answer:
52 da
Step-by-step explanation:
Whenever a question asks you, "How long to reach a certain concentration?" or something similar, you must use the appropriate integrated rate law expression.
The i<em>ntegrated rate law for a first-order reaction </em>is
ln([A₀]/[A] ) = kt
Data:
[A]₀ = 750 mg
[A] = 68 mg
t_ ½ = 15 da
Step 1. Calculate the value of the rate constant.
t_½ = ln2/k Multiply each side by k
kt_½ = ln2 Divide each side by t_½
k = ln2/t_½
= ln2/15
= 0.0462 da⁻¹
Step 2. Calculate the time
ln(750/68) = 0.0462t
ln11.0 = 0.0462t
2.40 = 0.0462t Divide each side by 0.0462
t = 52 da
The correct answer is ELECTRON. The part of an atom that is actively exchanged or shared in a chemical bond in the electron. Electron are negatively charged atoms.
The positive effect of using chemistry is the generation of energy without fossil fuels.
Chemistry is the branch of science that deals with the study of the nature, properties and composition of matter as well as the changes that matter undergoes. Chemistry has really contributed positively to the advancement of the society.
Lately, there has been a lot of emphasis on alternative sources of energy apart from fossil fuels. One such options is the use of hydrogen fuels. Chemistry has been at the forefront of this research.
Hence, one positive effect of using chemistry is that energy can be generated without burning fossil fuels.
Learn more: brainly.com/question/2192784
Answer:
gold and platinum
Explanation:
Very unreactive metals, such as gold and platinum, are found in the Earth's crust as pure metals. These are called native metals.
The molality of the toluene is 1.46 mol/kg.
<h3>
What is molality?</h3>
The molality of a solution is its molal concentration. Molal concentration is denoted by m. It is the mol of solute dissolves in 1 Kg solvent.
The depression at freezing point is directly proportional to the molality of the solution. The equation we use for this type of problem is:
ΔT=iKm 
Where, ΔT is depression at freezing point, i is Van't hoff factor, m is molality and 
is the freezing point depression constant.
Toluene is a non-electrolyte and so the value of i for this is 1.
Depression at a freezing point is given as -13.
and the is given as 5.12. So, we could calculate the molality of the solution using the equation written above.
Let's plug in the values in the equation:
ΔT=iKm
-7.51 =1 x5. 12 xm
m = 
m = 1.46 m
It means the molality of the solution is 1.46 mol/kg.
Hence, the molality of the solution is 1.46 mol/kg.
Learn more about the molality of the solution here:
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