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3 years ago

What is the percent yield if the theoretical yield is 256,5 g and the

Chemistry

1 answer:

KATRIN_1 [288]3 years ago

6 0

Answer:

78.9% yield

Explanation:

% Yield = Actual Lab Yield/Theoretical Yield x 100%

= (204.6g)/(256.5g)·100% = 79.8% Yield

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alculate the standard enthalpy of formation of ethanoic acid given that the standard enthalpy of combustion for carbon is –394 k

agasfer [191]

Answer:

The standard enthalpy of formation of ethanoic acid is -484 kJ/mol.

Explanation:

$C(g)+O_2(g)\rightarrow CO_2(g),\Delta H_{1, comb}=-394 kJ/mol$ ...[1]

$H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(l),\Delta H_{2, comb}=-286 kJ/mol$ ..[2]

$CH_3COOH(l)+2O_2(g)\rightarrow 2CO_2(g)+2H_2O(l),\Delta H_{3, comb}=-876 kJ/mol$ ..[3]

The standard enthalpy of formation of ethanoic acid :

$2C(g)+2H_2(g)+O_2(g)\rightarrow CH_3COOH, \Delta H_{4}=?$ ..[4]

Using Hess's law to calculate :

2 × [1] + 2 × [2] - [3] = [4]

$\Delta H_4=2\times (-394 kJ/mol)+2\times (-286 kJ/mol) - (-876 kJ/mol)$

$=\Delta H_4=-484 kJ/mol$

The standard enthalpy of formation of ethanoic acid is -484 kJ/mol.

5 0

3 years ago

Calculate the number of moles in 200 grams of Sodium hydroxide

TEA [102]

Answer:

The answer is 5 mol

Explanation:

Number Of Moles = Mass Of Substance ÷ Mass Of One Mole

Mass of NaOH = Molar Mass of Sodium + Oxygen + Hydrogen

23 + 16 + 1

40 g/mol

Number of Mole = 200/40 = 5 mol

Thus, The number of Moles in 200 grams of Sodium hydroxide is 5 mol

<u>-TheUnknownScientist 72</u>

6 0

3 years ago

What is the charge of the nucleus in boron

Reptile [31]

Answer:

Boron atoms lie in hexagonal aromatic graphite-like layers, with a charge of −1 on each boron atom. Magnesium (II) ions lie between layers Binary metal-boron compounds, the metal borides, contain boron in negative oxidation states. Illustrative is magnesium diboride (MgB 2).

Explanation:

8 0

3 years ago

How many kilograms of dry air are in a room that measures 15.0 ft by 18.0 ft by 8.00 ft? Use the density of air of 1.168 g/L. Th

Nady [450]

Answer:

0.0481 kg.

Explanation:

First, we need to find the volume of the room.

15 x 18 x 8 = 1350

The volume of the room is 1350 ft³

Now, we convert feet to centimeters

1350 x 30.48 = 41,148

The volume is 41,148 cm³

1 cm³ = 1 mL

So we can say that the volume of the room is also 41,148 mL

Then, we convert milliliters to liters

41,148 ÷ 1,000 = 41.148

There are 41.148 liters of air in the room

We multiply the air's density with volume in liters

41.148 x 1.168 = 48.060864

There are 48.060864 grams of air in the room

Finally, convert grams to kilograms

48.060864 ÷ 1,000 = 0.048060864

0.048060864 kilograms of air are in the room.

4 0

3 years ago

A 1.2 L weather balloon on the

makkiz [27]

Answer:

330.95K

Explanation:

V₁ = 1.2L

T₁ = 25°C = (25 + 273.15)K = 298.15K

P₁ = 1.0 atm

P₂ = 0.74 atm

V₂ = 1.8L

T₂ =?

From combined gas equation,

(P₁ * V₁) / T₁ = (P₂ * V₂) / T₂

Solve for T₂

T₂ = (P₂ * V₂ * T₁) / (P₁ * V₁)

T₂ = (0.74 * 1.8 * 298.15) / (1.0 * 1.2)

T₂ = 397.1358 / 1.2

T₂ = 330.9465K

T₂ = 330.95K or T₂ = (330.95 - 273.15)°C = 57.8°C

8 0

3 years ago