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lisov135 [29]
3 years ago
5

What is physical chemistry?

Chemistry
1 answer:
Drupady [299]3 years ago
4 0
Physical chemistry is a branch of chemistry that <span>concerns the application of theories and techniques of physics to the study of chemical study.</span>
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Numbers in scientific notation must be expressed in this form m times 10^n where
enot [183]

Answer:

Hi there I think the awnser is B. or A. lol but im 90% its A.

Explanation:

xoxo hope this helps

hugs and kisses also your pfp is hella cute:)

7 0
2 years ago
The half-life for beta decay of strontium-90 is 28.8 years. a milk sample is found to contain 10.3 ppm strontium-90. how many ye
ryzh [129]

Answer : The correct answer is 96.68 yrs

Radioactivity Decay :

it is a process in which a nucleus of unstable atom emit energy in form of radiations like alpha particle , beta particle etc .

Radioactive decay follows first order kinetics , so its rate , rate constant , amount o isotopes can be calculated using first order equations .

The first order equation for radioactive decay can be expressed as :

ln \frac{N}{N_0}  = - k*t ----------- equation (1)

Where : N = amount of radioisotope after time "t"

N₀ = Initial amount of radioisotope

k = decay constant and t = time

Following steps can be used to find time :

1) To find deacy constant :

Decay constant can be calculated using half life . Decay constant and half life can be related as :

T _\frac{1}{2} = \frac{ln2}{k} ---------equation (2)

Given : Half life of Strontium -90 = 28.8 years

Plugging value of T_\frac{1}{2} in above formula (equation 2) :

28.8 yrs = \frac{ln 2}{ k }

Multiply both side by k

28.8 yrs * k = \frac{ln 2 }{k} * k

Dividing both side by 28.8 yrs

\frac{28.8 yrs * k}{28.8 yrs} = \frac{ln 2}{28.8 yrs}

(ln 2 = 0.693 )

k = 0.0241 yrs⁻¹

Step 2 : To find time :

Given : N₀ = 10.3 ppm N = 1.0 ppm k = 0.0241 yrs⁻¹

Plugging these value in equation (1) as :

ln (\frac{1.0 ppm}{10.3 ppm} ) = - 0.0241 yrs^-^1 * t

ln (0.0971 ) = -0.0241 yrs ^-^1 * t

(ln 0.0971 = - 2.33 )

Dividing both side by - 0.0241 yrs⁻¹

\frac{-2.33}{-0.0241 yrs^-^1} = \frac{-0.0241 yrs^-^1 * t}{-0.0241 yrs^-^1}

t = 96.68 yrs

Hence the concentration of Strontium-90 will drop from 10.3 ppm to 1.0 ppm is 96.68 yrs

3 0
3 years ago
Read 2 more answers
Among the alkali earth metals, the tendency to react with other substances
tatyana61 [14]
Answer: option <span>A) increases from bottom to top within the group.

Explanation:

</span>It is a known trend that the metallic character of the elements increase from let to right and from top to bottom.

The greater the metallic character the greater the reactivity of the metal.

So, the elements of the columns 1 and 2 are the most reactive metals and among them the elements at the bottom are yet more reactive.

<span>The higher reactivity of the metals that are lower in the periodic table is attributed to the greater total number of electrons.

The greater the total number of electrons the more reactive the metals as their outermost electrons (the valence electrons which are those that react) are located further from the nucleus and therefore they are held less strongly, which makes them react more easily.</span>
5 0
3 years ago
Read 2 more answers
The The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k=0.029 W/ m measured temperature differ
vfiekz [6]

Answer:

Heat flux = 13.92 W/m2

Rate of heat transfer throug the 3m x 3m sheet = 125.28 W

The thermal resistance of the 3x3m sheet is 0.0958 K/W

Explanation:

The rate of heat transfer through a 3m x 3m sheet of insulation can be calculated as:

q=-k*A*\frac{\Delta T}{\Delta X}\\\\q=-0.029\frac{W}{m*K}*(3m*3m)*\frac{12K}{0.025m}  =125.28W

The heat flux can be defined as the amount of heat flow by unit of area.

Using the previous calculation, we can estimate the heat flux:

heat \, flux=\frac{q}{A}=\frac{125.28 W}{9 m^{2} }  =13.92 W/m^{2}

It can also be calculated as:

q/A=-k*\frac{\Delta T}{\Delta X}

The thermal resistance can be expressed as

\Delta T=R_t*Q\\R_t=\Delta T/Q=\frac{\Delta X}{k*A}

For the 3m x 3m sheet, the thermal resistance is

R_t = \frac{\Delta X}{k*A}=\frac{0.025m}{0.029W/mK*9m^{2}}=0.0958 \, K/W

4 0
3 years ago
Hydrochloric acid (HCl) and potassium hydroxide (KOH) react together in an aqueous solution. The reaction is an example of _____
artcher [175]
<span>A neutralization reaction.</span>
6 0
3 years ago
Read 2 more answers
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