¿Qué masa tiene un cuerpo que cuando se le aplica una fuerza de 20N se acelera 4m /s2?

What is the half-life (in seconds) of a zero-order reaction which has an initial reactant concentration of 0.884 M with a k valu

pantera1 [17]

Answer: 8.15s


Explanation:


1) A first order reaction is that whose rate is proportional to the concenration of the reactant:


r = k [N]


r = - d[N]/dt =


=> -d[N]/dt = k [N]


2) When you integrate you get:


N - No = - kt


3) Half life => N = No / 2, t = t'


=> No - No/ 2 = kt' => No /2 = kt' => t' = (No/2) / k


3) Plug in the data given: No = 0.884M, and k = 5.42x10⁻²M/s


t' = (0.884M/2) / (5.42x10⁻²M/s) = 8.15s

6 0

2 years ago

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What is the mass of HF produced by three reaction of 3.0 10 to the 23 molecules of H2 with excess F2

JulijaS [17]

Answer:

It is 20. g HF

Explanation:

H2 + F2 ==> 2HF ... balanced equation

Since the question is asking us to find the mass of product formed, we will want to first convert the molecules of H2 into moles of H2 (we could do this at the end of the calculations, but it's just as easy to do it now).

moles of H2 present (using Avogadro's number):

3.0x1023 molecules H2 x 1 mole H2/6.02x1023 molecules = 0.498 moles H2

From the balanced equation, we see that 1 mole H2 produces 2 moles HF. Therefore, we can now find the theoretical mass of HF produced from 0.498 moles H2:

0.498 moles H2 x 2 moles HF/1 mol H2 = 0.996 moles HF formed.

The molar mass of HF = 20.01 g/mole, thus...

0.996 moles HF x 20.01 g/mole = 19.93 g HF = 20. g HF formed (to 2 significant figures)

6 0

2 years ago

Given that the ka for hocl is 3.5 × 10–8, calculate the k value for the reaction of hocl with oh–.

Harlamova29_29 [7]

Following reaction is involved in above system
HOCl(aq) ↔ H+(aq) + OCl-(aq)
OCl-(aq) + H2O(l) ↔ HOCl(aq) + OH-(aq)

Now, if the system is obeys 1st order kinetics we have
K = [OCl-][H+]/[HOCl] ............. (1)
∴ [HOCl-] / [OCl-] = [H+] (1 / 3.0 * 10-8) ............. (2)

and now considering that system is obeying 2nd order kinetics, we have
K = [OH-][HOCl-] / [OCl-] ................. (3)
Subs 2 in 3 we get
K = [OH-][H+] (1 / 3.0 * 10-8)
we know that, [OH-][H+] = 10-14

∴K = 3.3 * 10-7

Thus, correct answer is e i.e none of these

6 0

3 years ago

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Which formula is an empirical formula?

poizon [28]

<h2>Hello!</h2>

The answer is:

The empirical formula is the option B. $NH_{3}$

The empirical formula of a compound is the simplest formula that can be written. On the opposite, the molecular formula involves a variant of the same compound, but it can be also simplified to an empirical formula.

$MolecularFormula=n(EmpiricalFormula)$

We are looking for a formula that cannot be simplified by dividing the number of molecules/atoms that conforms the compound.

Let's discard option by option in order to find which formula is an empirical formula (cannot be simplified)

A. $N_{2}O_{4}$

It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

$N_{2}O_{4}=2(NO_{2})$

B. $NH_{3}$

It's an empirical formula since it cannot be obtained by the multiplication of a whole number and the simplest formula. It's the simplest formula that we can find of the compound.

C. $C_{3}H_{6}$