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:

3.48 x 1013 N2 molecules

step-by-step explanation:

Lets set up our equation first

P = 1.00 x 10-6 mm Hg T = 0.0° C + 273 = 273 K

We are given the V = 985 mL ,

R = 0.0821 L·atm/mol·K

Now use the ldeal gas law, but we are solving n, amount of substanvce

PV = nRT, we will change this equation to ;

n = PV/RT

n = 1.00 x 10-6 mm x 1 atm/760 mm x 985 mL x 1 L/103

mL/

(0.0821 L·atm/mol·K x 273 K) = 5.78 x 10-11 moles N2

nmolecules = 5.78 x 10-11 moles N2 x 6.02 x 1023 N2 molecules/1 mol N2

Answer:

0.307

Explanation:

use the formula of n=mass /molar mass

Answer:

You would add its kinetic and potential energies.

Explanation:

Hope this helps!! :)

Answer:

A) Add its kinetic and potential energies

Explanation:

I got it right on Edge 2022

Answer:

There are 6 Carbon dioxides, and 6 waters, but there are 6 carbons, 18 oxygens, and 12 hydrogens.

Explanation:

Answer:

6 carbon atoms

18 oxygen atoms

12 hydrogen atoms

Answer:

1 gram of N2 is equal to 0.035697202053303 mole. i dont know the rest but intried to help

. hopefully this will give you someone else a starting point. goodluck

Answer:

Explanation:

Let the final volume be v .

from the formula

S₁ V₁ = S₂V₂

4 x 7 = .8 x V₂

V₂ = 35 mL

Final volume of the solution will be 35 mL .

Answer:

33

Explanation:

Answer:

[tex]Y=75.6\%[/tex]

Explanation:

Hello.

In this case, since no information about the reacting hydrogen is given, we can assume that it completely react with the 28.0 g of acetylene to yield ethane. In such a way, via the 1:1 mole ratio between acetylene (molar mass = 26 g/mol) and ethane (molar mass = 30 g/mol), we compute the yielded grams, or the theoretical yield of ethane as shown below:

[tex]m_{C_2H_6}^{theoretical}=28.0gC_2H_2*\frac{1molC_2H_2}{26gC_2H_2}*\frac{1molC_2H_6}{1molC_2H_2} *\frac{30gC_2H_6}{1molC_2H_6}\\ \\m_{C_2H_6}^{theoretical}=32.3gC_2H_6[/tex]

Hence, by knowing that the percent yield is computed via the actual yield (24.5 g) over the theoretical yield, we obtain:

[tex]Y=\frac{24.5g}{32.3g}*100\%\\ \\Y=75.6\%[/tex]

Best regards.

Answer:

The electrons are found on the outer shell of the atom.

Explanation:

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:

A=element

B=compond

C=solution

Answer:

D. 9.

Explanation:

Mass number of an atom is the sum of the proton number and neutron number. For Be, the protons are 4 and neutrons are 5. So, we get 9 by adding them.

Answer:

LA PRIMERA ES N

Explanation:

Answer:

The disruption of the bonds or attractions occurs during protein hydrolysis which results in the loss for the primacy structure. The peptide bonds is the bond affected in this scenario.

The disruption of the bonds however only exist in the process of denaturation and this results in a change in the confirmation which could be secondary, tertiary, and quaternary structural related. And example of the bonds affected include salt bridges, disulfide bridges, hydrogen bonds etc.

Answer:

0.013 mol/L

Explanation:

Molarity, which is molar concentration or moles per unit volume, can be calculated using the formula:

M = n/V

Where; M = Molar concentration of solution

n = number of moles of solute

V = Volume of solvent

n = 0.0025 moles of sugar

V = 200.00mL of solution

Since 0.001L = 1mL

200mL = 0.200L

Therefore, M = n/V

M = 0.0025/0.200

M = 0.0125 mol/L

Round up to the nearest thousandth ~ 0.013mol/L

Answer:

high melting points, dissolve easily in water, conduct electricity when melted.

Explanation:

I'm pretty sure

Answer:

We are given that there is 95% ethanol by mass in rectified spirit

so, we can say that in a 100g sample, we have 95 grams of ethanol and 5 grams of water

we will find the number of moles of ethanol and water in 100g solution of rectified spirit and use that to calculate the mole fraction

Moles of Ethanol:

Molar mass of ethanol = 46 grams / mol

Number of moles = Given mass / molar mass

Number of moles = 95 / 46

Moles of Ethanol = 2 moles (approx)

Moles of Water:

Molar mass of water = 18 grams per mol

Number of moles = Given mass / molar mass

Moles of water = 5 / 18

Moles of water  =  0.28 moles   (approx)

Mole Fractions:

Mole fraction of a specific compound is the number of moles of that compound divided by the total number of moles in the solution

Mole fraction of Ethanol:

Moles of ethanol / (moles of ethanol + moles of water)

2 / (2 + 0.28)

2 / (2.28) = 0.9 (approx)

Mole fraction of Water:

Moles of water / (Moles of ethanol + moles of water)

0.28 / (2 + 0.28)

0.28 / (2.28) = 0.1 (approx)

Answer:

Pb2+(aq) + 2Cl–(aq) ----> PbCl2(s)

Explanation:

The net ionic equation shows the main reaction that takes place in a system. Hence, a net ionic equation focusses only on those species that actually participate in the reaction.

For the reaction between Pb(NO3)2 and NH4Cl , the net ionic equation is;

Pb^+(aq) + 2Cl^-(aq) ---> PbCl2(s)

The correct net ionic equation for the reaction that occurs when solutions of Pb(NO₃)₂ and NH₄Cl are mixed is

To know the the correct net ionic equation for the reaction that occurs when solutions of Pb(NO₃)₂ and NH₄Cl are mixed, we shall write the net ionic equation for the reaction. This is illustrated below:

Pb(NO₃)₂(aq) —> Pb⁺(aq) + NO₃¯(aq)

NH₄Cl(aq) —> NH₄⁺(aq) + Cl¯(aq)

Pb(NO₃)₂(aq) + NH₄Cl(aq) —>

Pb⁺(aq) + NO₃¯(aq) + NH₄⁺(aq) + Cl¯(aq) —> PbCl₂(s) + NO₃¯(aq) + NH₄⁺(aq)

Cancel the spectator ions (i.e NO₃¯ and NH₄⁺) and write 2 before Cl¯ to obtain the net ionic equation as shown below:

Thus, the correct net ionic equation for the reaction that occurs when solutions of Pb(NO₃)₂ and NH₄Cl are mixed is

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Answer:

strong base

Explanation:

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Answer:

53/26Fe = 0/-1,B + 53/27 Co

Answer:

1. Faster

Explanation:

Answer:

Explanation:

Here you go!! Hope this helps.

Answer:

CO = 1.320 x 10¹¹ Kg  

NOx = 1.942 x 10¹⁰ Kg

HC = 1.592 x 10¹⁰ Kg  

Explanation:

Given that;

there are approximately 250 million passenger vehicles

each is driven 25,000 km per year which is 15534.28 miles per year

In 1970, the  vehicular emission norms are;

CO = 34 g/mile , NOx = 5 g/mile , HC = 4.1 g/mile

so emission of CO in 1970 is;

250000000 × 15534.28 × 34 g

= 1.320 x 10¹⁴ g

= 1.320 x 10¹¹ Kg  

Also, emission of NOx in 1970

250000000 × 15534.28 × 5 g

= 1.9417 x 10¹³ g

= 1.942 x 10¹⁰ Kg

emission of HC in 1970

= 250000000 × 15534.28 × 4.1 g  

= 1.5922 x 10¹³ g

= 1.592 x 10¹⁰ Kg  

Answer:

valence electrons

Explanation:

The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for .

The chemical element which contains four (4) electrons in its third and outer main energy level is: Silicon (Si).

An electron shell can be defined as the outermost shell of an atom of a chemical element around the atomic nucleus.

Hence, an electron shell is an orbital that is typically accompanied by electrons around the nucleus of an atom.

A sublevel is also referred to as an orbital and it can be defined as an energy level that is associated with the electrons found outside the atomic nucleus.

In Chemistry, there are four main (4) types of sublevel and these are:

In the third (3rd) energy level, there are only three (3) sublevels and these are; s, p and d sublevels.

Silicon is a chemical element that is found in group (4) of the periodic table because it has four (4) electrons in its third and outermost shell.  

In its ground state, Silicon (Si) contains the following number of electrons:

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Answer:

I am sure they are why won't they