What is the main responsibility of scientists when enviermental laws are proposed?

A second-order reaction has a rate law: rate = k[a]2, where k = 0.150 m−1s−1. If the initial concentration of a is 0.250 m, what

Cerrena [4.2K]

Rate law for the given 2nd order reaction is:

Rate = k[a]2

Given data:

rate constant k = 0.150 m-1s-1

initial concentration, [a] = 0.250 M

reaction time, t = 5.00 min = 5.00 min * 60 s/s = 300 s

To determine:

Concentration at time t = 300 s i.e. $[a]_{t}$

Calculations:

The second order rate equation is:

$1/[a]_{t} = kt +1/[a]$

substituting for k,t and [a] we get:

1/[a]t = 0.150 M-1s-1 * 300 s + 1/[0.250]M

1/[a]t = 49 M-1

[a]t = 1/49 M-1 = 0.0204 M

Hence the concentration of 'a' after t = 5min is 0.020 M

7 0

3 years ago

[15 Points, Stoichiometry and Gases]

KiRa [710]

The reaction is

CaC₂(s) + 2H₂O (l) -----> Ca(OH)₂ (s) + C₂H₂ (g)

As we have data of gas ethyne (or acetylene), C₂H₂

We can calculate the moles of acetylene and from this we can estimate the mass of calcium carbide taken

the moles of acetylene will be calculated using ideal gas equation

PV =nRT

R = gas constant = 0.0821 Latm/molK

T = 385 K

V = volume = 550 L

P = Pressure = 1.25 atm

n = moles = ?

n = PV /RT = 1.25 X 550 / 0.0821 X 385 = 21.75 mol

As per balanced equation these moles of acetylene will be obtained from same moles of calcium carbide

moles of calcium carbide = 21.75mol

molar mass of CaC₂ = 40 + 24 = 64

mass of CaC₂ = moles X molar mass = 21.75 X 64 = 1392g

6 0

3 years ago

Read 2 more answers

Muscles undergo fermentation when no carbon dioxide is available. no oxygen is available. no pyruvate is available. no water is

Komok [63]

When no oxygen is available

8 0

3 years ago

How many moles of Cu(OH)2 are soluble in 1L of sodium hydroxide (NaOH) when the pH is 8.23?

Morgarella [4.7K]

Answer:

4.96E-8 moles of Cu(OH)2

Explanation:

Kps es the constant referring to how much a substance can be dissolved in water. Using Kps, it is possible to know the concentration of weak electrolytes. Then, pKps is the minus logarithm of Kps.

Now, we know that sodium hydroxide (NaOH) is a strong electrolyte, who is completely dissolved in water. Therefore the pH depends only on OH concentration originating from NaOH. Let us to figure out how much is that OH concentration.

$pH= -log[H]\\pH= -log (\frac{kw}{[OH]})$

$8.23 = - log(\frac{Kw}{[OH]} \\10^{-8.23} = Kw/[OH]\\ [OH] = Kw/10^{-8.23}$

$[OH]=1.69E-6$

This concentration of OH affects the disociation of Cu(OH)2. Let us see the dissociation reaction:

$Cu(OH)_2 -> Cu^{2+} + 2OH^-$

In the equilibrum, exist a concentration of OH already, that we knew, and it will be added that from dissociation, called "s":

The expression for Kps is:

$Kps= [Cu^{2+}] [OH]^2$

The moles of (CuOH)2 soluble are limitated for the concentration of OH present, according to the next equation.

$Kps= s*(2s+1.69E-6)^2$

"s" is the soluble quantity of Cu(OH)2.

The solution for this third grade equation is $s=4.96E-8 mol/L$

Now, let us calculate the moles in 1 L:

$moles Cu(OH)_2 = 4.96E-8 mol/L * 1 L = 4.96E-8 moles$

7 0

4 years ago

Although Rutherford is credited with the famous gold foil scattering experiment, he didn’t actually conduct this experiment hims

Dmitrij [34]

Although he did not do the experiment himself, he had come up with the idea of what to do and how to do it. I think that only Rutherford receiving credit is okay as the assistants did not do anything to contribute to the actual idea of the experiment.
For example, we credit the invention of the iPhone to Steve Jobs, the engineers of Apple, the designers, etc. - those with actual contributions to the invention and the ideas and not the Chinese factory workers - those who construct the iPhone itself.

3 0

4 years ago