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1 year ago

4

You might have noticed that new copper roofs turn green over time. This occurs because copper reacts with substances in the air

to form a hard, protective coating. Will the mass of the new copper roof increase or decrease over time? Explain. Does this prediction violate the law of conservation of mass? Explain. (4 marks)

1 answer:

irga5000 [103]1 year ago

8 0

Answer:

the mass of the new copper roof will increase over time as it turns green

Explanation:

this is because copper will react with atmospheric substances to form copper compound. this does not violate the law of conversation of mass because the mass increases as copper react with atmospheric substances in the presence of atmospheric air, oxidizes to copper compounds which are heavier in mass than copper atoms

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penicillin. an important antibiotic (antibacterial agent), was discovered accidentally by the scottish bacteriologist alexander

dmitriy555 [2]

Answer:

mass percent of carbon = 57.78 %

mass percent of hydrogen = 6.40 %

mass percent of nitrogen = 8.96 %

mass percent of oxygen = 20.49 %

mass percent of sulfur = 10.24 %

Explanation:

Given data

Molecular formula = C₁₄H₂₀N₂O₄S

molecular mass (total mass) = 312.39 g/mol

Percentage of carbon = ?

Percentage of hydrogen = ?

Percentage of oxygen = ?

Percentage of nitrogen = ?

Percentage of sulfur = ?

Solution

1st we find out number of moles of each element from the molecular formula

Number of moles of carbon = 14 mol

Number of moles of hydrogen = 20 mol

Number of moles of nitrogen = 2 mol

Number of moles of oxygen = 4 mol

Number of moles of sulfur = 1 mol

Now we find out the mass of each element

as we know that

<em>mass = number of moles × molecular mass</em>

mass of carbon = 14 mol × 12 g/mol

mass of carbon = 168 g

mass of hydrogen = 20 mol × 1 g/mol

mass of hydrogen = 20 g

mass of nitrogen = 2 mol × 14 g/mol

mass of nitrogen = 28 g

mass of oxygen = 4 mol × 16 g/mol

mass of oxygen = 64 g

mass of sulfur = 1 mol × 32 g/mol

mass of sulfur = 32 g

now we find out the mass percent of each element

<em> mass percent = ( mass ÷ total mass ) × 100</em>

mass percent of carbon = ( 168 g ÷ 312.39 g/mol ) × 100

mass percent of carbon = 57.78 %

mass percent of hydrogen = ( 20 g ÷ 312.39 g/mol ) × 100

mass percent of hydrogen = 6.40 %

mass percent of nitrogen = ( 28 g ÷ 312.39 g/mol ) × 100

mass percent of nitrogen = 8.96 %

mass of oxygen =( 64 g ÷ 312.39 g/mol ) × 100

mass percent of oxygen = 20.49 %

mass percent of sulfur = ( 32 g ÷ 312.39 g/mol ) × 100

mass percent of sulfur = 10.24 %

7 0

2 years ago

A graduated cylinder holds 100 mL of water. A lead weight is dropped into the cylinder bringing the new volume up to 450 mL. If

dolphi86 [110]

11.43g/mL

Explanation:

Given parameters:

Volume of water in the graduated cylinder = 100mL

Volume of water + lead weight = 450mL

Mass of lead weight = 4000g

Unknown:

Density of the lead weight = ?

Solution:

Density is the mass per unit volume of a body.

Density = $\frac{mass}{volume}$

Volume of the lead weight = volume of water displaced

Volume of lead weight = 450 - 100 = 350mL

Density = $\frac{4000}{350}$ = 11.43g/mL

learn more:

Density brainly.com/question/2690299

#learnwithBrainly

6 0

2 years ago

Which of the samples described below contains the FEWEST atoms? No calculation is needed to answer this question.

Monica [59]

Hello!

To do this, use the molar mass. This is how much a mole of an atom weighs. A mole is 6.02214076×10²³ atoms.

Molar masses of:

Se: 78.96 g/mol

Cu: 63.546 g/mol

Ba: 137.327 g/mol

Now, the element with the highest molar mass will have the fewest atoms. This is because the element weighs more, so therefore for the same amount of mass, there will be less of the element needed to reach that mass.

Therefore, 10g of Ba would have the fewest number of atoms.

Hope this helps!

6 0

2 years ago

Which equation shows the proper setup to find the volume of a 0.250 M CaCl2 solution that contains 39.5 g of CaCl2?

Jlenok [28]

Molarity = number of mole of substance(n) / volume of solution (V).

n(CaCl2) = mass (CaCl2)/M(CaCl2)

M(CaCl2) = 40+2*35.5 = 111 g/mol

n(CaCl2) =39.5 g CaCl2*1 mol/111g

0.250 M = 39.5 g CaCl2*1 mol/111g*volume of solution (V).

volume of solution (V) = 39.5 g CaCl2*1 mol/(0.250 M*111g) = 1.42 L

4 0

2 years ago

Read 2 more answers

The reaction SO2(g)+2H2S(g)←→3S(s)+2H2O(g) is the basis of a suggested method for removal of SO2 from power-plant stack gases. T

kifflom [539]

Answer : The equilibrium $SO_2$ pressure is, $3.93\times 10^{-5}torr$

Explanation :

The given balanced chemical reaction is,

$SO_2(g)+2H_2S(g)\rightleftharpoons 3S(s)+2H_2O(g)$

First we have to calculate the standard free energy of reaction $(\Delta G^o)$ .

$\Delta G^o=G_f_{product}-G_f_{reactant}$

$\Delta G^o=[n_{S(s)}\times \Delta G_f^0_{(S(s))}+n_{H_2O(g)}\times \Delta G_f^0_{(H_2O(g))}]-[n_{SO_2(g)}\times \Delta G_f^0_{(SO_2(g))}+n_{H_2S(g)}\times \Delta G_f^0_{(H_2S(g))}]$

where,

$\Delta G^o$ = standard free energy of reaction = ?

n = number of moles

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

$\Delta G^o=[3mole\times (0kJ/mol)+2mole\times (-228.57kJ/mol)]-[1mole\times (-300.4kJ/mol)+2mole\times (-33.01kJ/mol)]$

$\Delta G^o=-90.72kJ/mol$

Now we have to calculate the value of $K_p$

$\Delta G^o=-RT\ln K_p$

where,

$\Delta G_^o$ = standard Gibbs free energy = -90.72 kJ/mol

R = gas constant = 8.314 J/mole.K

T = temperature = 298 K

$K_p$ = equilibrium constant = ?

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

$-90.72kJ/mol=-(8.314J/mol.K)\times (298K) \ln K_p$

$K_p=7.98\times 10^{15}$

Now we have to calculate the value of $K_p$ .

The given balanced chemical reaction is,

$SO_2(g)+2H_2S(g)\rightleftharpoons 3S(s)+2H_2O(g)$

The expression for equilibrium constant will be :

$K_p=\frac{(p_{H_2O})^2}{(p_{H_2S})^2\times (p_{SO_2})}$

In this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.

Let the equilibrium $SO_2$ pressure be, x

Pressure of $SO_2$ = Pressure of $H_2S$ = x

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

$7.98\times 10^{15}=\frac{(22)^2}{(x)^2\times (x)}$

$x=3.93\times 10^{-5}torr$

Thus, the equilibrium $SO_2$ pressure is, $3.93\times 10^{-5}torr$

4 0

2 years ago