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2 years ago

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An object will sink in a liquid if the density of the object is greater than that of the liquid. the mass of a sphere is 9.83 g.

if the volume of this sphere is less than ________ cm3, then the sphere will sink in liquid mercury (density = 13.6 g/cm3).

1 answer:

lord [1]2 years ago

5 0

The volumeof this sphere must be less than 0.7228

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Exactly 1.0 mol N2O4 is placed in an empty 1.0-L container and allowed to reach equilibrium described by the equation N2O4(g) 2N

Amanda [17]

Answer : The correct option is, (a) 0.44

Explanation :

First we have to calculate the concentration of $N_2O_4$ .

$\text{Concentration of }N_2O_4=\frac{\text{Moles of }N_2O_4}{\text{Volume of solution}}$

$\text{Concentration of }N_2O_4=\frac{1.0moles}{1.0L}=1.0M$

Now we have to calculate the dissociated concentration of $N_2O_4$ .

The balanced equilibrium reaction is,

$N_2O_4(g)\rightleftharpoons 2NO_2(aq)$

Initial conc. 1.0 M 0

At eqm. conc. (1.0-x) M (2x) M

As we are given,

The percent of dissociation of $N_2O_4$ = $\alpha$ = 28.0 %

So, the dissociate concentration of $N_2O_4$ = $C\alpha=1.0M\times \frac{28.0}{100}=0.28M$

The value of x = $C\alpha$ = 0.28 M

Now we have to calculate the concentration of $N_2O_4\text{ and }NO_2$ at equilibrium.

Concentration of $N_2O_4$ = 1.0 - x = 1.0 - 0.28 = 0.72 M

Concentration of $NO_2$ = 2x = 2 × 0.28 = 0.56 M

Now we have to calculate the equilibrium constant for the reaction.

The expression of equilibrium constant for the reaction will be:

$K_c=\frac{[NO_2]^2}{[N_2O_4]}$

Now put all the values in this expression, we get :

$K_c=\frac{(0.56)^2}{0.72}=0.44$

Therefore, the equilibrium constant $K_c$ for the reaction is, 0.44

8 0

2 years ago

A 10.0-ml sample of 0.200 m hydrocyanic acid (hcn) is titrated with 0.0998 m naoh. what is the ph at the equivalence point? for

tatyana61 [14]

When the titration of HCN with NaOH is:

HCN (aq) + OH- (aq) → CN-(aq) + H2O(l)

So we can see that the molar ratio between HCN: OH-: CN- is 1:1 :1

we need to get number of mmol of HCN = molarity * volume

= 0.2 mmol / mL* 10 mL = 2 mmol

so the number of mmol of NaOH = 2 mmol according to the molar ratio

so, the volume of NaOH = moles/molarity

= 2 mmol / 0.0998mL

= 20 mL

and according to the molar ratio so, moles of CN- = 2 mmol

∴the molarity of CN- = moles / total volume

= 2 mmol / (10mL + 20mL ) = 0.0662 M

when we have the value of PKa = 9.31 and we need to get Pkb

so, Pkb= 14 - Pka

= 14 - 9.31 = 4.69

when Pkb = -㏒Kb

4.69 = -㏒ Kb

∴ Kb = 2 x 10^-5

and when the dissociation reaction of CN- is:

CN-(aq) + H2O(l) ↔ HCN(aq) + OH- (aq)

by using the ICE table:

∴ the initials concentration are:

[CN-] = 0.0662 M

and [HCN] = [OH]- = 0 M

and the equilibrium concentrations are:

[CN-] = (0.0662- X)

[HCN] = [OH-]= X

when Kb expression = [HCN][OH-] /[CN-]

by substitution:

2 x 10^-5 = X^2 / (0.0662 - X)

X = 0.00114

∴[OH-] = X = 0.00114

when POH = -㏒[OH]

= -㏒ 0.00114

POH = 2.94

∴PH = 14 - 2.94 = 11.06

6 0

2 years ago

Determine the empirical formula for succinic acid that is composed of 40.60% carbon, 5.18% hydrogen, and 54.22% oxygen.

aleksklad [387]

Answer:

C₂H₂O₃

Explanation:

The empirical formula of a compound is derived bu finding the whole ratios of the constituent elements.

In succinic acid, the ratios of carbon to hydrogen to oxygen is calculated as follows:

<u>% mass</u>

Carbon- 40.60

Hydrogen - 5.18

Oxygen - 54.22

<u>RAM</u>

Carbon -12

Oxygen - 15.994

Hydrogen -1.008

<u>No of moles elements in the compound</u>

Carbon = 40.60/12=3.3833

Oxygen = 54.22/15.994= 3.39

Hydrogen= 5.18/1.008 = 5.1389

Mole ratios of the individual elements we divide by the smallest value of the number of moles.

Carbon: Hydrogen : Oxygen

3.3833/3.3833:3.39/3.3833:5.1389/3.3833

=1:1:1.5

We can multiply the value by 2 to get the whole number ratio.

=2:2:3

The empirical formula will be:

C₂H₂O₃

5 0

2 years ago

An atom of lead has a radius of and the average orbital speed of the electrons in it is about . Calculate the least possible unc

victus00 [196]

The question is incomplete. Here is the complete question.

An atom of lead has a radius of 154 pm and the average orbitalspeed of the electron in it is about 1.8x $10^{8}$ m/s. Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of lead. Write your answer as a percentage of the average speed, and round it to significant 2 digits.

Answer: v% = 0.21 m/s

Explanation: To calculate the uncertainty, use <u>Heisenberg's Uncertainty Principle</u>, which states that: ΔpΔx≥ $\frac{h}{4\pi }$

where h is <u>Planck's constant</u> and it is equal to 6.626. $10^{-34}$ m²kg/s.

Since p (momentum) is p = m.v:

mΔv.Δx ≥ $\frac{h}{4\pi }$

Δv = $\frac{h}{4\pi.x.m }$

Given that: r = x = 1.54. $10^{-10}$ m and mass of an electron is m=9.1. $10^{-31}$ kg

Δv = $\frac{6.626.10^{-34} }{4.3.14.1.54.10^{-10}.9.1.10^{-31}}$

Δv = 0.0376. $10^{7}$

As percentage of average speed:

Δv. $\frac{1}{v}$ .100% = $\frac{0.0376.10^{7} }{1.8.10^{8} }$ .10² = 0.021.10 = 0.21%

The least possible uncertainty in a speed of an electron is 0.21%.

5 0

2 years ago

Karen has discovered a new organism in the Amazon Rainforest. It moves by itself, is a consumer, and its cells do not have a cel

EastWind [94]

The correct answer is option B, that is, Animalia.

The animals refer to the multicellular eukaryotic species, which forms the biological kingdom known as Animalia. The majority of the animals breathe oxygen, consume organic substances, and possess the tendency to move, has the tendency to reproduce, and develop from a hollow sphere of cells, the blastula at the time of embryonic development. In comparison to Kingdom Plantae, the cells in animals do not exhibit cell wall. Thus, on the basis of the characteristics, the newly discovered species must be categorized under Kingdom Animalia.

3 0

2 years ago