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2 years ago

Please help asap please. thanks :)

Chemistry

1 answer:

Feliz [49]2 years ago

8 0

Answer:

phosphorus (P)

Explanation:

this is because when we add

2+2+6+2+3

we get 15

15 is also the atomic number so when we check the periodic table, we know phosphorus has an atomic number of 15 therefore the answer is phosphorus.

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The following reaction was monitored as a function of time: AB-->A+B A plot of 1/AB versus time yields a straight line with s

dexar [7]

Answer:

half-life = 31.3 s

0.123 M A, 0.123 M B

Explanation:

When they tell us that a graph of 1 /[AB] versus time yields a straight line, they are telling us that the reaction is first order repect to AB.

A first order rection has a form:

rate = - ΔA/Δt = - k[A]²

The integrated rate law for this equation from calculus is:

1/[A]t = kt+ 1/[A]₀

which we see is the equation of a line with slope k and y intercept 1/[A]₀

Therefore k = 5.5 10⁻² /Ms

The above equation can rewritten as:

1/ (1/2 [A]₀) = k t1/2 + 1/[A]₀

2/[A]₀ = k t1/2 + 1/[A]₀

and the half life will be given by:

t 1/2 = 1 / k[A]₀

t 1/2 = 1 / [( 5.5 x 10⁻² /Ms ) x 0.58 M]

t 1/2 = 31.3 s

For the second part we make use of the equation from above:

1/[A]t = kt+ 1/[A]₀

to determine [A]t, and from the stoichiometry of the reaction we will calculate how much of A and B has been produced.

1/[A]t = ( 5.5 x 10⁻²/Ms) x 80s + 1/0.240 M

1/[A]t = 4.40 / M + 4.167 / M = 8.56 / M

⇒ [A]t = 0.117 M

If after 80 seconds we have 0.117 M of AB, this means (0.240 - 0.117) of AB reacted to produce 0.123 M of A and .123 M of B.

It maybe a bit confusing that we almost have half of our original concentration of AB, and from the first part we know the half-life was 31.3 s.

But, you have to realize that the half-life for second order reactions depend on the initial concentration ( different from first order ). Calculating the half life in this part with an original concentration of 0.240 M gives us a half-life of 75.8 s which makes sense with our result.

7 0

3 years ago

Which two organisms contain chloroplasts and eyespots?

arsen [322]

there are more to this than just two of those. the answer is volvox and euglena

5 0

4 years ago

Read 2 more answers

In a coffee-cup calorimeter, 1.60 g of NH4NO3 was mixed with 75.0 g of water at an initial temperature of 25.008C. After dissolu

jekas [21]

Answer:

Explanation:

mass of the solution m = 1.6 + 75 = 76.6 g

fall in temperature = 25 - 23.34 = 1.66°C

heat absorbed = mass x specific heat x fall in temperature

= 76.6 x 1.66 x 4.18

= 531.5 J .

= .5315 kJ .

mol weight of ammonium nitrate = 80 g

heat absorbed by 1.6 g = .5315 kJ

heat absorbed by 80 g or one mole = 26.575 kJ

enthalpy change ΔH = +26.575 kJ

b )

enthalpy of hydration = 2630 kJ / mol

lattice energy = enthalpy of hydration + enthalpy change

= 2630 + 26.575

= 2656.575 kJ .

7 0

3 years ago

The mass of a solid substance is 21.1164 g. If the volume of

GuDViN [60]

Answer:

The density of the substance is 1.0611 $\frac{g}{cm^{3} }$

Explanation:

The density of a substance is a characteristic property that matter, whether solids, liquids or gases, has to be compressed in a given space, that is, it allows us to measure the amount of mass in a certain volume of a substance.

Density is expressed as follows:

$density=\frac{mass}{volume}$