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4 years ago

Why is red the last color seen at sunset?

1 answer:

8 0

Within the visible range of light, red light waves are scattered the least by atmospheric gas molecules. So at sunrise and sunset, when the sunlight travels a long path through the atmosphere to reach our eyes, the blue light has been mostly removed, leaving mostly red and yellow light remaining.

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In certain conditions, the equilibrium concentrations for components in the reaction 2NOCl(g) 2NO(g) + Cl2(g) are [NO] = 0.02 M,

Sonja [21]

Keq= (products)/ (reactants)

Keq= ( [NO]^2 x [Cl2]) / ( [NOCl]^2)

Keq= ( (0.02)^2 x (0.01) ) / (0.5)^2= 1.6 x 10-5

8 0

3 years ago

Hi, I'm lost on which ones to choose on this CHEM Problem.

DaniilM [7]

Answer:

✓no change in the composition of the platinum could be detected

3 0

3 years ago

a certain anesthetic contains 64.9% C, 13.5% H, and 21.6% O by mass. at 120 deg Celsius & 750 mmHg, 1.00 L of the gaseous co

slamgirl [31]

You need to use the % information to determine the empirical formula of the compound first.

The empirical formula is the simplest ratio of atoms in the molecule.

Then use the rest of the data to determine moles of gas, and use this to determine molar mass of gas...

Empirical formula calculations:

Assume you have 100 g, calculate the moles of each atom in the 100 g

moles = mass / molar mass
molar mass C = 12.01 g/mol
molar mass H = 1.008 g/mol
molar mass O = 16.00 g/mol

C = 64.9 % = 64.6 g
H = 13.5 % = 13.5 g
O = 21.6 % = 21.6 g

moles C = 64.6 g / 12.01 g/mol = 5.38 mol
moles H = 13.5 g / 1.008 g/mol = 13.39 mol
moles O = 21.6 g / 16.00 g/mol = 1.35 mol

So ratio of C : H : O
is 5.38 mol : 13.39 mol : 1.35 mol

Divide each number in the ratio by the lowest number to get the simplest whole number ratio

(5.38 / 1.35) : (13.39 / 1.35) : (1.35 / 1.35)

4 : 10 : 1

empirical formula is
C4H10O

Finding moles and molar mass calcs

Now, you know that at 120 deg C and 750 mmHg that 1.00L compound weighs 2.30 g.

We can use this information to determine the molar mass of the gas after first working out how many moles the are in the 1.00 L

PV = nRT
P = pressure = 750 mmHg
V = volume = 1.00 L
n = moles (unknown)
T = temp in Kelvin (120 deg C = (273.15 + 120) Kelvin)
- T = 393.15 Kelvin
R = gas constant, which is 62.363 mmHg L K^-1 mol^-1 (when your P is in mmHg and volume is in L)

n = PV / RT
n = (750 mmHg x 1.00 L) / (62.363mmHg L K^-1 mol^-1 x 393.15 K)
n = 0.03059 moles of gas

We know moles = 0.03509 and mass = 2.30 g
So we can work out molar mass of the gas

moles = mass / molar mass
Therefore molar mass = mass / moles
molar mass = 2.30 g / 0.03059 mol
= 75.19 g/mol

Determine molecular formula

So empirical formula is C4H10O
molar mass = 75.19 g/mol

To find the molecular formula you divide the molar mass by the formula weight of the empirical formula...
This tells you how many times the empirical formula fits into the molecular formula. Tou then multiply every atom in the empirical formula by this number

formula weight C4H10O = 74.12 g/mol

Divide molar mass by formula weight empirical
75.15 g/mol / 74.12 g/mol
= 1
(It doesn't matter that the number don't quite match, they rarely do in this type of calc (although I could have made a slight error somewhere) but the numbers are very close, so we can say 1.)

The empirical formula only fits into the molar mass once,

molecular formula thus = empirical formula

C4H10O

Therefore, the molecular formula of the compound is C4H10O.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

5 0

3 years ago

How much excess reactant is left over when 17.0 g of potassium hydroxide (KOH) reacts with

dolphi86 [110]

Answer:

4.56 g of KOH

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

2KOH + Fe(NO₃)₂ —> Fe(OH)₂ + 2KNO₃

Next, we shall determine the masses of KOH and Fe(NO₃)₂ that reacted from the balanced equation. This is can be obtained as:

Molar mass of KOH = 39 + 16 + 1 = 56 g/mol

Mass of KOH from the balanced equation = 2 × 56 = 112 g

Molar mass of Fe(NO₃)₂ = 56 + 2[14 + (16×3)]

= 56 + 2[14 + 48)]

= 56 + 2[62]

= 56 + 124

= 180 g/mol

Mass of Fe(NO₃)₂ from the balanced equation = 1 × 180 = 180 g

SUMMARY:

From the balanced equation above,

112 g of KOH reacted with 180 g of Fe(NO₃)₂

Next, we shall determine the limiting reactant and the excess reactant. This can be obtained as follow:

From the balanced equation above,

112 g of KOH reacted with 180 g of Fe(NO₃)₂.

Therefore, 17 g of KOH will react with = (17 × 180)/112 = 27.32 g of Fe(NO₃)₂

From the calculations made above, we can see that it will take a higher mass (i.e 27.32 g) of Fe(NO₃)₂ than what was given (i.e 20 g) to react completely with 17 g of KOH.

Therefore, Fe(NO₃)₂ is the limiting reactant and KOH is the excess reactant.

Next, we shall determine the mass of the excess reactant that reacted. This can be obtained as follow:

From the balanced equation above,

112 g of KOH reacted with 180 g of Fe(NO₃)₂.

Therefore Xg of KOH will react with 20 g of Fe(NO₃)₂ i.e

Xg of KOH = (112 × 20)/180

Xg of KOH = 12.44 g

Thus, 12.44 g of KOH reacted.

Finally, we shall determine the leftover mass of the excess reactant.

The excess reactant is KOH. The leftover mass can be obtained as follow:

Mass of KOH given = 17 g

Mass of KOH that reacted = 12.44 g

Mass of KOH leftover =?

Mass of KOH leftover = (Mass of KOH given) – (Mass of KOH that reacted)

Mass of KOH leftover = 17 – 12.44

Mass of KOH leftover = 4.56 g

Thus, the excess reactant (i.e KOH) that is left over is 4.56 g

3 0

3 years ago

An atom of alluminum has an atomic number of 13 and a mass of a mass number lf 27. How many neutrons does it have?

Alex777 [14]

Answer:

13 Neutrons

Explanation:

8 0

3 years ago

Read 2 more answers