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2 years ago

The density of gold is 19.32. Give two reasons why this statement is incomplete

Chemistry

2 answers:

makvit [3.9K]2 years ago

6 0

Answer: The units and conditions are not written.

Explanation:

Density is defined as the ratio of mass of a substance to the volume of substance. The equation used to calculate density of a substance follows:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

This property is expressed in g/mL or kg/L

Density depends on temperature and pressure of the system.

As, the temperature of the system increases, the particles move freely which increases the volume of system and leads to the decrease of density.

As, the pressure of the system increase, the particles come closer to one another which decreases the volume of system and leads to the increase of density.

So, for the given value of density, two reasons are:

Units are not given.
Conditions are not mentioned.

DerKrebs [107]2 years ago

3 0

A: there is no unit. b: it doesn't present the temperature and pressure

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For the reaction 2N2O5(g) <---> 4NO2(g) + O2(g), the following data were colected:

KonstantinChe [14]

Answer:

a) The reaction is first order, that is, order 1. Option C is correct.

b) The half life of the reaction is 23 minutes. Option B is correct

c) The initial rate of production of NO2 for this reaction is approximately = (3.7 × 10⁻⁴) M/min. Option has been cut off.

Explanation:

First of, we try to obtain the order of the reaction from the data provided.

t (minutes) [N2O5] (mol/L)

0 1.24x10-2

10 0.92x10-2

20 0.68x10-2

30 0.50x10-2

40 0.37x10-2

50 0.28x10-2

70 0.15x10-2

Using a trial and error mode, we try to obtain the order of the reaction. But let's define some terms.

C₀ = Initial concentration of the reactant

C = concentration of the reactant at any time.

k = rate constant

t = time since the reaction started

T(1/2) = half life

We Start from the first guess of zero order.

For a zero order reaction, the general equation is

C₀ - C = kt

k = (C₀ - C)/t

If the reaction is indeed a zero order reaction, the value of k we will obtain will be the same all through the set of data provided.

C₀ = 0.0124 M

At t = 10 minutes, C = 0.0092 M

k = (0.0124 - 0.0092)/10 = 0.00032 M/min

At t = 20 minutes, C = 0.0068 M

k = (0.0124 - 0.0068)/20 = 0.00028 M/min

At t = 30 minutes, C = 0.0050 M

k = (0.0124 - 0.005)/30 = 0.00024 M/min

It's evident the value of k isn't the same for the first 3 trials, hence, the reaction isn't a zero order reaction.

We try first order next, for first order reaction

In (C₀/C) = kt

k = [In (C₀/C)]/t

C₀ = 0.0124 M

At t = 10 minutes, C = 0.0092 M

k = [In (0.0124/0.0092)]/10 = 0.0298 /min

At t = 20 minutes, C = 0.0068 M

k = 0.030 /min

At t = 30 minutes, C = 0.0050 M

k = 0.0303

At t = 40 minutes

k = 0.0302 /min

At t = 50 minutes,

k = 0.0298 /min

At t = 60 minutes,

k = 0.031 /min

This shows that the reaction is indeed first order because all the answers obtained hover around the same value.

The rate constant to be taken will be the average of them all.

Average k = 0.0302 /min.

b) The half life of a first order reaction is related to the rate constant through this relation

T(1/2) = (In 2)/k

T(1/2) = (In 2)/0.0302

T(1/2) = 22.95 minutes = 23 minutes.

c) The initial rate of production of the product at the start of the reaction

Rate = kC (first order)

At the start of the reaction C = C₀ = 0.0124M and k = 0.0302 /min

Rate = 0.0302 × 0.0124 = 0.000374 M/min = (3.74 × 10⁻⁴) M/min

3 0

1 year ago

If 4.9 kg of CO2 are produced during a combustion reaction, how many molecules of CO2 would be produced?

solmaris [256]

Answer:

6.7 x 10²⁶molecules

Explanation:

Given parameters

Mass of CO₂ = 4.9kg = 4900g

Unknown:

Number of molecules = ?

Solution:

To find the number of molecules, we need to find the number of moles first.

Number of moles = $\frac{mass}{molar mass}$

Molar mass of CO₂ = 12 + 2(16) = 44g/mol

Number of moles = $\frac{4900}{44}$ = 111.36mole

A mole of substance is the quantity of substance that contains the avogadro's number of particles.

1 mole = 6.02 x 10²³molecules

111.36 moles = 111.36 x 6.02 x 10²³molecules = 6.7 x 10²⁶molecules

5 0

2 years ago

Why does silver iodide have a higher melting point than vanillin

MAVERICK [17]

AgI has a higher melting point than vanillin because it is an ionic compound. The bonds are held more tightly together than in vanillin because it is a covalent compound. Ionic bonds have a higher melting point because the electrons are being transferred from one atom to the other.

5 0

2 years ago

According to the following balanced reaction, how many moles of HNO3 are formed from 8.44 moles of NO2 if there is plenty of wat

kotegsom [21]

Answer:

5.63 mol.

Explanation:

The balanced chemical equation between NO₂ and H₂O is:

3NO₂(s) + H₂O(l) → 2HNO₃(aq) + NO(g),

It is clear that 3 mol of NO₂ reacts with 1 mol of H₂O to produce 2 mol of HNO₃ and 1 mol of NO.

Water is present as an excess reactant and NO₂ is limiting reactant.

To find the no. of moles of HNO₃ produced:

3 mol of NO₂ produces → 2 mol of HNO₃, from stichiometry.

8.44 mol of NO₂ produces → ??? mol of HNO₃.

∴ The no. of moles of HNO₃ are formed = (8.44 mol)(2 mol)/(3 mol) = 5.63 mol.

3 0

2 years ago

Most Bic lighters hold 5.0ml of liquified butane (density = 0.60 g/ml). Calculate the minimum size container you would need to "

Hatshy [7]

Answer:

Volume of container = 0.0012 m³ or 1.2 L or 1200 ml

Explanation:

Volume of butane = 5.0 ml

density = 0.60 g/ml

Room temperature (T) = 293.15 K

Normal pressure (P) = 1 atm = 101,325 pa

Ideal gas constant (R) = 8.3145 J/mole.K)

volume of container V = ?

Solution

To find out the volume of container we use ideal gas equation

PV = nRT

P = pressure

V = volume

n = number of moles

R = gas constant

T = temperature

First we find out number of moles

As Mass = density × volume

mass of butane = 0.60 g/ml ×5.0 ml

mass of butane = 3 g

now find out number of moles (n)

n = mass / molar mass

n = 3 g / 58.12 g/mol

n = 0.05 mol

Now put all values in ideal gas equation

PV = nRt

V = nRT/P

V = (0.05 mol × 8.3145 J/mol.K × 293.15 K) ÷ 101,325 pa

V = 121.87 ÷ 101,325 pa

V = 0.0012 m³ OR 1.2 L OR 1200 ml

8 0

2 years ago