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4 years ago

85 POINTS!!

Chemistry

1 answer:

Gelneren [198K]4 years ago

6 0

Answer:

It says in the question its up to you to decide, so you have to graph the weather changes then explain why you graphed it in that way.

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The standard free energy of activation of a reaction A is 81.9 kJ mol–1 (19.6 kcal mol–1) at 298 K. Reaction B is one million ti

klasskru [66]

Answer:

54.9 kJ/mol

Explanation:

The relation between the activation energy (Ea) and the rate constant (k) is given by the Arrhenius equation.

$k=A.e^{-Ea/RT}$

where,

A is a collision factor

R is the ideal gas constant

T is the absolute temperature

Reaction B is one million times faster than reaction A at the same temperature. So $k_{B}=10^{6} k_{A}$ .

Then,

$k_{B}=10^{6} k_{A}\\A.e^{-Ea_{B}/RT}=10^{6}A.e^{-Ea_{A}/RT}\\e^{-Ea_{B}/RT}=10^{6}e^{-Ea_{A}/RT}\\ln(e^{-Ea_{B}/RT})=ln(10^{6}e^{-Ea_{A}/RT})\\\frac{-Ea_{B}}{RT} =ln10^{6} -\frac{Ea_{A}}{RT} \\Ea_{B}=(ln10^{6} -\frac{Ea_{A}}{RT}).(-RT)=(ln10^{6}-\frac{89.1kJ/mol}{(8.314\times 10^{-3} kJ/mol.K).298K} ).(-8.314\times 10^{-3} \frac{kJ}{mol.K}.298K )=54.9kJ/mol$

8 0

3 years ago

Need help on #129. Please help!

MrRissso [65]

The percentage yield is 72.8 %.

Step 1. Calculate the mass of Br₂

Mass of Br₂ = 20.0 mL Br₂ × (3.10 g Br₂/1 mL Br₂) = 62.00 g Br₂

Step 2. Calculate the theoretical yield

M_r: 159.81 266.69

2Al + 3Br₂ → 2AlBr₃

Moles of Br₂ = 62.00 g Br₂ × (1 mol Br₂/(159.81 g Br₂) = 0.3880 mol Br₂

Moles of AlBr₃ = 0.3880 mol Br₂ × (2 mol AlBr₃/(3 mol Br₂) = 0.2586 mol AlBr₃

Theor. yield of AlBr₃ = 0.2586 mol AlBr₃ × 266.99 g AlBr₃)/(1 mol AlBr₃)

= 69.05 g AlCl₃

Step 3. Calculate the percentage yield

% yield = (actual yield/theoretical yield) × 100 % = (50.3 g/69.05 g) × 100 %

= 72.8 %

5 0

3 years ago

Students in physics class are asked to find the relationship between the length of a pendulum (string with a weight at the botto

Goshia [24]

Answer:

1) $Time \ for \ pendulum \ swing \ left \ and \ right = 2 \times \pi \times \sqrt{\dfrac{Length \ of \ the \ pendulum \ string}{g} }$

2) The dependent variable = The time it takes for one pendulum swing

3) The independent variable = The length of the pendulum string with weight at the bottom

Explanation:

The relationship between the length of the pendulum string and the time it takes for one pendulum swing is giving as follows;

$T = 2 \cdot \pi \cdot \sqrt{\dfrac{L}{g} }$

Where;

T = The period of oscillation = The time to complete one oscillation =Two swings of the pendulum

L = The length of the pendulum

g = The acceleration due to gravity

Therefore, the time it takes for one pendulum swing is directly proportional to the square root of the length of the pendulum

The dependent variable = The time it takes for one pendulum swing

Th independent variable = The length of the pendulum string with weight at the bottom.

5 0

4 years ago

The little dipper is located in:

tamaranim1 [39]

The little dipper is located in Ursa Minor you would also get a clue because... Minor and little

8 0

3 years ago

In which situation would the momentum of a moving object increase?

kupik [55]

Answer:

Explanation:

D. A force acting in the direction opposite the object’s motion is removed from the object

3 0

2 years ago