State Hess' law of constant heat summation.
(b) Calculate the enthalpy of formation of CH4 from the following data:
i) C(s) + O2(g) → CO2(g); ∆H = -393.7 kJ/mol
ii) H2(g) + 1⁄2 O2(g) → H2O(l); ∆H = -285.8 kJ/mol
iii) CH4(g) + 2 O2(g)→ CO2(g) + 2H2O(l); ∆H = -890.4 kJ/mol

Answer:

Protons,electrons,and neutrons make up matter

Explanation:

i studied this so hope it helps

Answer:

the ball will move towards the big bully

Answer:

False

Explanation:

It is the other way round, a black object appears black because it absorbs all the wavelength of light and does not reflect any light.

Answer:

0.3125 g

Explanation:

Given data:

Half life of barium-122 = 2 min

Mass of sample = 10.0 g

Mass of barium remain after 10 min = ?

Solution:

Number of half lives = Time elapsed / half life

Number of half lives = 10 min/ 2 min

Number of half lives = 5

At time zero = 10 g

At 1st half life = 10 g/2 = 5 g

At 2nd half life = 5 g/2 = 2.5 g

At 3rd half life = 2.5 g/2 = 1.25 g

At 4th half life = 1.25 g/2 = 0.625 g

At 5th half life = 0.625 g/2 = 0.3125 g

Answer:

The equilibrium concentration of NO is 0.02124 M.

Explanation:

Given that,

Initial concentration of NOBr = 0.878 M

[tex]k_{c}=3.07\times10^{-4}[/tex]

Temperature = 24°C

We know that,

The balance equation is

[tex]2NOBr\Rightarrow 2NO+Br_{2}[/tex]

Initial concentration is,

[tex]0.878\Rightarrow 0+0[/tex]

Concentration is,

[tex]-2x\Rightarrow 2x+x[/tex]

Equilibrium concentration

[tex]0.878-2x\Rightarrow 2x+x[/tex]

We need to calculate the value of x

Using formula of concentration

[tex]k_{c}=\dfrac{[NO][Br_{2}]}{[NOBr]^2}[/tex]

Put the value into the formula

[tex]3.07\times10^{-4}=\dfrac{[2x][x]}{[0.878-2x]^2}[/tex]

[tex]2x^2=3.07\times10^{-4}\times(0.878)^2+3.07\times10^{-4}\times4x^2-2\times2x\times0.878\times3\times10^{-4}[/tex]

[tex]2x^2=0.0002367+0.001228x^2-0.0010536x[/tex]

[tex]2x^2-0.001228x^2+0.0010536x-0.0002367=0[/tex]

[tex]1.998772x^2+0.0010536x-0.0002367=0[/tex]

[tex]x=0, 0.01062[/tex]

We need to calculate the equilibrium concentration of NO

Using formula of concentration of NO

[tex]concentration\ of\ NO=2x[/tex]

Put the value of x

[tex]concentration\ of\ NO=2\times0.01062[/tex]

[tex]concentration\ of\ NO=0.02124[/tex]

Hence, The equilibrium concentration of NO is 0.02124 M.

Answer:

Waves is the disturbance or variation that transfer energy from one location to other

Answer:

this is not in my words but i think this will help

(put some of the words you would use in this)

Explanation:

Transverse waves are always characterized by particle motion being perpendicular to wave motion. A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction that the wave moves. ... Longitudinal waves are always characterized by particle motion being parallel to wave motion.

hope i helped

Answer:

D - Nucleus to Cell

Explanation:

Hope it helps!!

:D

Answer:

35.1% is percent yield

Explanation:

Full question: Assume no volume change.  If you formed 0.0910 atm of gas, what is the percent yield?

The reaction that is occurring is:

Ni + 3HBr → NiBr₃ + 3/2H₂(g)

First, we will determine moles of Ni and HBr to determine limiting reactant and theoretical yield

Using ideal gas law, we can determine the moles of hydrogen formed. Thus, we can find percent yield:

Moles Ni (Molar mass: 58.69g/mol):

1.02g * (1mol / 58.69g) = 0.01738moles Ni

Moles HBr:

0.750L * (0.112mol/L) = 0.084 moles of HBr.

For a complete reaction of the 0.084 moles of HBr you need:

0.084mol HBr * (1 mole Ni / 3 moles HBr) = 0.028 moles of Ni.

As there are just 0.01738 moles of Ni, the Ni is limiting reactant. Assuming a theoretical yield, moles of H₂ produced are:

0.01738moles Ni * (3/2 H₂ / 1 mol Ni) = 0.02607 moles H₂

Now, moles of H₂ produced are:

PV = nRT

PV/RT = n

Where P is pressure (0.0910atm)

V is volume (2.50L)

R is gas constant (0.082atmL/molK)

T is absolute temperature in Kelvin (30°C + 273.15 = 303.15K)

And n are moles

PV/RT = n

0.0910atm*2.50L/0.082atmL/molK*303.15K = n

0.00915 moles = n

And percent yield (Produced moles / Theoretical moles * 100) is:

0.00915 moles / 0.02607moles =

Explanation:

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Answer:

20 protons.

Explanation:

20 protons = 20 + charges

18 electrons = 18- charges.

The difference = 20 - 18 = +2

The charge for this ion is plus 2

It is a calcium ion. The element is number 20 on the periodic table.

The charge of the ion is +2

HOW TO DETERMINE THE CHARGE OF AN ION:

Therefore, the charge of the ion will be 20 protons - 18 electrons = +2

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Answer:

Insoluble benzoic acid is formed

Explanation:

When benzoic acid is dissolved in sodium hydroxide solution, sodium benzoate is formed. This compound is highly soluble in the aqueous layer.

If this solution is now acidified, the equilibrum position shifts towards the undissociated benzoic acid and a precipitate appears.

An insoluble substance formed during crystallization or precipitation is called a precipitate. The precipitate of the reaction formed is of benzoic acid.

A precipitation reaction is a type of reaction in which an insoluble salt or substance is formed as the result of the reaction between the soluble salt solutions.

The substance or the salt produced that does not get dissolved in the solution is called a precipitate.

In the reaction, benzoic acid reacts with the sodium hydroxide salt and forms sodium benzoate salt as shown,

[tex]\rm C_{6}H_{5}COOH(s) + NaOH(aq) \rightarrow C_{6}H_{5}COO^{-}Na^{+}(aq) + H_{2}O(l)[/tex]

When the salt of sodium benzoate is acidified then the precipitation of benzoic acid is formed. The precipitate occurs because the equilibrium shifts towards the undissociated benzoic acid.

Therefore, a precipitate of benzoic acid is formed.

Learn more about precipitation here:

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Answer:

162.4

Explanation:

The formula for mass is density* volume so 62.7 multiplied by 2.59 equals 162.393. then you round so your anwser would be 162.4

Answer:If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2.

If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375.

Explanation:

Answer:

CO < BF < KI < LiF

Explanation:

The magnitude of ionic character in a bond is dependent on the magnitude of electronegativity difference between the atoms in the bond.

Remember that no bond is 100% ionic or covalent according to Linus Pauling. However, the percentage ionic character depends on electronegativity difference between the bonding atoms and polarizability (Fajan's rules).

Between LiF and KI, Fajan's rules become very important. The Li^+ is small and highly polarizing.  The stronger the polarising power of the cation and the higher the polarisability of the anion the more covalent character is expected in a bond

Answer:

C

Explanation:

Hope this helps :)

Answer:

Elements are the simplest complete chemical substances. Each element corresponds to a single entry on the periodic table. An element is a material that consists of a single type of atom. Each atom type contains the same number of protons.

Chemical bonds link elements together to form more complex molecules called compounds. A compound consists of two or more types of elements held together by covalent or ionic bonds.

Explanation:

Answer:

15.9994 grams

You can view more details on each measurement unit: molecular weight of Oxygen or grams The molecular formula for Oxygen is O. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Oxygen, or 15.9994 grams.

Explanation:

Answer:

First you need to know the Chemical formula for Nitrous acid which is HNO₂

Explanation:

Answer:

1. The pH of 1.0 M trimethyl ammonium (pH = 1.01) is lower than the pH of 0.1 M phenol (5.00).

2. The difference in pH values is 4.95.

Explanation:

1. The pH of a compound can be found using the following equation:

[tex] pH = -log([H_{3}O^{+}]) [/tex]

First, we need to find [H₃O⁺] for trimethyl ammonium and for phenol.

Trimethyl ammonium:

We can calculate [H₃O⁺] using the Ka as follows:

(CH₃)₃NH⁺ + H₂O  →  (CH₃)₃N + H₃O⁺    

1.0 - x                               x           x  

[tex]Ka = \frac{[(CH_{3})_{3}N][H_{3}O^{+}]}{[(CH_{3})_{3}NH^{+}]}[/tex]

[tex] 10^{-pKa} = \frac{x*x}{1.0 - x} [/tex]

[tex] 10^{-9.80}(1.0 - x) - x^{2} = 0 [/tex]    

By solving the above equation for x we have:  

x = 0.097 = [H₃O⁺]

[tex] pH = -log([H_{3}O^{+}]) = -log(0.097) = 1.01 [/tex]                                      

Phenol:

C₆H₅OH + H₂O → C₆H₅O⁻ + H₃O⁺

1.0 - x                        x             x

[tex]Ka = \frac{[C_{6}H_{5}O^{-}][H_{3}O^{+}]}{[C_{6}H_{5}OH]}[/tex]

[tex] 10^{-10} = \frac{x^{2}}{1.0 - x} [/tex]

[tex] 1.0 \cdot 10^{-10}(1.0 - x) - x^{2} = 0 [/tex]

Solving the above equation for x we have:

x = 9.96x10⁻⁶ = [H₃O⁺]

[tex] pH = -log([H_{3}O^{+}]) = -log(9.99 \cdot 10^{-6}) = 5.00 [/tex]

Hence, the pH of 1.0 M trimethyl ammonium is lower than the pH of 0.1 M phenol.

2. The difference in pH values for the two acids is:

[tex] \Delta pH = pH_{C_{6}H_{5}OH} - pH_{(CH_{3})_{3}NH^{+}} = 5.00 - 1.01 = 4.95 [/tex]

Therefore, the difference in pH values is 4.95.

I hope it helps you!

Answer:

iodine pentachloride

Explanation:

Answer:

look at the explanation

Explanation:

The air that you breathe is a homogeneous mixture of oxygen, nitrogen, argon, and carbon dioxide, along with other elements in smaller amounts. Because each layer of the Earth's atmosphere has a different density, each layer of air is its own homogeneous mixture.

Hope this helps. :)

Answer:

What are we talking about here?

Explanation: