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3 years ago

What trend in atomic radius do u see as you go a group family on the periodic table?

Chemistry

2 answers:

exis [7]3 years ago

7 0

Atomic radius increases down a group

emmainna [20.7K]3 years ago

6 0

What trend in the atomic radius do you see as you go a group family on the periodic table ... it increases

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For a particular isomer of C 8 H 18 , C8H18, the combustion reaction produces 5104.1 kJ 5104.1 kJ of heat per mole of C 8 H 18 (

vlada-n [284]

Answer:

The standard enthalpy of formation of this isomer of octane is -220.1 kJ/mol

Explanation:

Step 1: Data given

The combustion reaction of octane produces 5104.1 kJ per mol octane

Step 2: The balanced equation

C8H18(g) + 12.5 O2 ⟶ 8CO2 (g) + 9 H2O (g) ∆H°rxn = -5104.1 kJ/mol

Step 3:

∆H°rxn = ∆H°f of products minus the ∆H° of reactants

∆H°rxn = ∆H°f products - [∆H°f reactants]

-5104.1 kJ/mol = (8*∆H°fCO2 + 9*∆H°fH20) - (∆H°fC8H18 + 12.5∆H°fO2)

∆H°f C8H18 = ∆H°f 8CO2 + ∆H°f 9H2O+ 5104.1 kJ/mol

∆H°f C8H18 = 8 * (-393.5 kJ)/mol + 9 * (-241.8 kJ/mol)] + 5104.1 kJ /mol

∆H°f C8H18 = -220.1 kJ/mol

The standard enthalpy of formation of this isomer of octane is -220.1 kJ/mol

7 0

3 years ago

Which statements describe Newton and the law of universal gravitation? Check all that apply.

jonny [76]

Answer:

Newton believed that gravity was a force.

The law of universal gravitation offers a mathematical explanation for the attraction between the moon and Earth.

Newton was the first to have the idea that gravity is everywhere.

8 0

3 years ago

Read 2 more answers

Is first order in ch3nc. the half life of the reaction is 5.20 101 s at 545 k. the rate constant when the initial [ch3nc] is 0.0

Katyanochek1 [597]

I need help too anyone got the answer?

7 0

3 years ago

Calculate the pH for each of the cases in the titration of 25.0 mL of 0.180 M pyridine, C 5 H 5 N ( aq ) with 0.180 M HBr ( aq )

Oxana [17]

Answer:

Explanations

Calculate the pH for each of the following cases in thetitration of 25.0 mL of 0.100 M pyridine, C5H5N(aq) with 0.100 MHBr(aq):

a.Before and addition of HBr

b.After addition of 12.5ml HBr

c.After addition of 15ml HBr

d.After addition of 25ml HBr

e.After addition of 33ml HBr

SOLUTION ;;;

Kb of pyridine =1.5*10^-9

a)let the dissociation be x.so,

kb=x^2/(0.1-x)

or 1.5*10^-9=x^2/(0.1-x)

or x=1.225*10^-5

so,

[OH-]=1.225*10^-5

so,

pOH=-log([OH-])

so pH=9.088

b)now this will effectively behave as a buffer

pKb=8.82

so pOH=pKb+log(salt/acid)

=8.82+log((12.5*0.1)/(25*0.1-12.5*0.1))

=8.82

so pH=14-pOH

=5.18

c)again using the same equation as the above,

pOH=pKb+log(salt/acid)

=8.82+log((15*0.1)/(25*0.1-15*0.1))

so pH=14-9

d)now the base is completely neutralised.so,

concentration of the salt formed=0.1/2

=0.05 M

so,

pH=7-0.5pKb-0.5log(C)

=7-0.5*8.82-0.5*log(0.05)

=3.24

e)concentration of H+=(33*0.1-25*0.1)/(33+25)

=0.01379

so pH=-log(0.01379)

=1.86

4 0

3 years ago

Read 2 more answers

A chemist dissolves 797. mg of pure barium hydroxide in enough water to make up 60. mL of solution. Calculate the pH of the solu

topjm [15]

Answer:

13.20

Explanation:

Step 1: Calculate the moles of Ba(OH)₂

The molar mass of Ba(OH)₂ is 171.34 g/mol.

0.797 g × 1 mol/171.34 g = 4.65 × 10⁻³ mol

Step 2: Calculate the molar concentration of Ba(OH)₂

Molarity is equal to the moles of solute divided by the liters of solution.

[Ba(OH)₂] = 4.65 × 10⁻³ mol/60 × 10⁻³ L = 0.078 M

Step 3: Calculate [OH⁻]

Ba(OH)₂ is a strong base according to the following equation.

Ba(OH)₂ ⇒ Ba²⁺ + 2 OH⁻

The concentration of OH⁻ is 2/1 × 0.078 M = 0.16 M

Step 4: Calculate the pOH

pOH = -log OH⁻ = -log 0.16 = 0.80

Step 5: Calculate the pH

We will use the following expression.

pH + pOH = 14

pH = 14 - 0.80 = 13.20

7 0

3 years ago