Sponges, Cnidarians, Flatworms, and Roundworms are all in which group of animals?

Suppose the half-life is 9.0 s for a first order reaction and the reactant concentration is 0.0741 M 50.7 s after the reaction s

bazaltina [42]

<u>Answer:</u> The time taken by the reaction is 84.5 seconds

<u>Explanation:</u>

The equation used to calculate half life for first order kinetics:

$k=\frac{0.693}{t_{1/2}}$

where,

$t_{1/2}$ = half-life of the reaction = 9.0 s

k = rate constant = ?

Putting values in above equation, we get:

$k=\frac{0.693}{9}=0.077s^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$ ......(1)

where,

k = rate constant = $0.077s^{-1}$

t = time taken for decay process = 50.7 sec

$[A_o]$ = initial amount of the reactant = ?

[A] = amount left after decay process = 0.0741 M

Putting values in equation 1, we get:

$0.077=\frac{2.303}{50.7}\log\frac{[A_o]}{0.0741}$

$[A_o]=3.67M$

Now, calculating the time taken by using equation 1:

$[A]=0.0055M$

$k=0.077s^{-1}$

$[A_o]=3.67M$

Putting values in equation 1, we get:

$0.077=\frac{2.303}{t}\log\frac{3.67}{0.0055}\\\\t=84.5s$

Hence, the time taken by the reaction is 84.5 seconds

6 0

3 years ago

How many moles of N2 in 57.1 g of N2?

SpyIntel [72]

We are given –

Mass of $\bf N_2$ is 57.1 g and we are asked to find number of moles present in 57.1 g of $\bf N_2$

$\qquad$ $\pink{\bf\longrightarrow { Molar \:mass \:of \: N_2:-} }$

$\qquad$ $\bf \twoheadrightarrow 14\times 2$

$\qquad$ $\bf \twoheadrightarrow 28$

$\qquad$ ____________________

Now,Let's calculate the number of moles present in 57.1 g of $\bf N_2$

$\qquad$ $\purple{\bf\longrightarrow { No \:of \:moles = \dfrac{Given \:mass}{Molar\: mass}}}$

$\qquad$ $\bf \twoheadrightarrow \dfrac{57.1}{28}$

$\qquad$ $\bf \twoheadrightarrow 2.04\: moles$

__________________________________

7 0

2 years ago

What is the molarity if I take 10mL of 20 volumes Hydrogen Peroxide?

Kryger [21]

Answer:

1.635 M

Explanation:

Given:

10 mL of 20 volumes Hydrogen Peroxide

Here,

20 volumes of Hydrogen Peroxide means that on decomposition of 1 mL of H₂O₂ 20 mL of O₂ is obtained

also,

means 1 dm³ of H₂O₂ solution produces 20 dm³ oxygen

Now,

at 298K and 1 atm

20 dm³ oxygen = $\frac{\textup{20}}{\textup{24.47}}$ moles

or

= 0.817 moles

also,

2H₂O₂ → 2H₂O + O₂

thus,

1 dm³ of solution must contain 2 × moles of O₂ as moles of H₂O₂

thus,

Number of moles of H₂O₂ = 2 × 0.817

or

Number of moles of H₂O₂ = 1.635 moles

Hence,

For 20 volume hydrogen peroxide is 1.635 M

3 0

3 years ago

1. A sample of polystyrene is found to have a number-average molar mass of 89,440 g mol−1 . Neglecting contributions from end gr

Snowcat [4.5K]

Answer:

The weight-average molar mass of polystyrene is 134,160 g/mol.

Explanation:

Molar mass of the monomer styrene , $C_8H_8$ , M=104 g/mol

Given , number average molar mass of the polymer , M'= 89,440 g/mol

Degree of polymerization = n

$n=\frac{M'}{M}=\frac{89,440 g/mol}{104 g/mol}=860$

The weight-average molar mass = $M_{avg}=?$

Molar mass dispersity is ratio of weight-average molar mass to the number average molar mass of the polymer.

$\text{Molar mass dispersity}=\frac{M_{avg}}{M'}$

$1.5=\frac{M_{avg}}{89,440 g/mol}$

$M_{avg}=89,440 g/mol\times 1.5 = 134,160 g/mol$

The weight-average molar mass of polystyrene is 134,160 g/mol.

8 0

2 years ago

What percentage of known species are invertebrates?

ehidna [41]

95 percent of species known are invertebrates

6 0

2 years ago