Answer:
174.8 g/m is the molar mass of the solute
Explanation:
We must apply colligative property of freezing point depression.
ΔT = Kf . m . i
ΔT = T° freezing pure solvent - T° freezing solution (0° - (-2.34°C) = 2.34°C
Kf = Fussion constant for water, 1.86 °C/m
As ascorbic acid is an organic compound, we assume that is non electrolytic, so i = 1
2.34°C = 1.86°C/m . m
2.34°C / 1.86 m/°C = 1.26 m
This value means the moles of vitamin C, in 1000 g of solvent
We weighed the solute in 250 g of solvent, so let's calculate the moles of vitamin C.
1000 g ___ 1.26 moles
In 250 g ___ (250 . 1.26)/1000 = 0.314 moles
This are the moles of 55 g of ascorbic acid, so the molar mass, will be:
grams / mol ⇒ 55 g/0.314 m = 174.8 g/m
(a) The temperature goes up by 3⁰C.
(b) There is increase in temperature, so the reaction is exothermic.
(c) Examples of exothermic reaction include, rusting of Iron, burning of coal, reaction of strong acid and water.
(d) Examples of endothermic reaction include, melting solid salts and evaporating liquid water.
<h3>
What is exothermic reaction?</h3>
Exothermic reaction is a type of chemical reaction in which energy is transferred to or from the surroundings.
Examples of exothermic reactions include the following;
- Rusting of Iron
- Burning of Coal
- Reaction of Strong Acid and Water
- Water and Calcium Chloride
<h3>What is endothermic reaction?</h3>
Endothermic reaction is a type of chemical reaction in which energy is absorbed from the surroundings.
Examples of endothermic reactions include the following;
- Melting solid salts.
- Evaporating liquid water, etc
<h3>Change in temperature</h3>
From the increase in temperature from 15⁰C to 23⁰C, we can conclude that the temperature goes up by 3⁰C.
20⁰C - 17⁰C = 23⁰ - 20⁰C = 3⁰C.
Since there is increase in temperature, the reaction is exothermic.
Learn more about exothermic reaction here: brainly.com/question/2924714
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-1.09'C is the change in freezing point
“Freezing point depression” depends on the solvent and the molar concentration of the solute.
Sulfide is highly basic, consequently
K2S
completely and irreversibly hydrolyzes in water according to the following equation:
K2S+H2O→KOH+KSH
<h3>What is freezing?</h3>
Freezing, also known as solidification, is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point.
the temperature at which a liquid solidifies specifically : the temperature at which the liquid and solid states of the substance are in equilibrium at atmospheric pressure : melting point the freezing point of water is 0° Celsius or 32° Fahrenheit.
Learn more about change in freezing point here:brainly.com/question/23035406
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Answer: There are 3.2 moles of gas if you have a volume of 38.0 L under a pressure of 1430 mmHg at standard temperature.
Explanation:
Given: Volume = 38.0 L
Pressure = 1430 mm Hg (1 mm Hg = 0.00131579 atm) = 1.9 atm
Temperature = 273.15 K
Using ideal gas equation, the moles of gas will be calculated as follows.
where,
P = pressure
V = volume
n = no. of moles
R = gas constant = 0.0821 L atm/mol K
T =temperature
Substitute the values into above formula as follows.
Thus, we can conclude that there are 3.2 moles of gas if you have a volume of 38.0 L under a pressure of 1430 mmHg at standard temperature.
