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The boiling point of water is 100.0°C at 1 atmosphere. How many grams of sodium acetate (82.04 g/mol), must be dissolved in 283.

Alecsey [184]

Answer:

I have to weight 10,04 g of acetate sodium

Explanation:

This is the colligative propertie about elevation of boiling point

ΔT = Kb . m . i

ΔT is the difference between T° at boiling point of the solution - T° at boiling point of the solvent pure - we have this data 0,450°C

Kb means ebulloscopic constant (0,52 °C.kg/m .- a known value for water)

m means molality (moles of solute in 1kg of solvent)

i means theVan 't Hoff factor (degree of dissociation for a compound)

For the sodium acetate is 2

NaCH3COO ---> Na+ + CH3COO-

0,450°C = 0,52°C.kg/m . m . 2

0,450°C / (0,52°C.kg/m . 2) = m

0,432 m/kg = m

This number means I have 0,432 moles of acetate sodium, my solute in 1kg of water, my solvent. But I don't have 1000 g (1kg) I only have 283 g so let's make the rule of three:

1000 g _____ 0,432 moles

283 g ______ (283g .0,432m) / 1000g = 0,122 moles

Now that I have the moles of acetate sodium, I have to find the mass.

Moles . molar mass = mass

0,122 moles . 82.04 g/mol = 10,04 g

3 0

4 years ago

Read 2 more answers

According to the cooling curve, what is the approximate freezing point of the substance?

Dmitry_Shevchenko [17]

Correct answer: B

Cooling curve is the plot of temperature versus time as the sample is allowed to cool. In a cooling curve, we start at a temperature greater than the boiling point. At this temperature, the sample is in gaseous state. At the boiling point, there is no change in temperature as the gaseous and liquid states are in equilibrium. As the temperature reduces further, the liquid starts to condense and at the melting point of the sample the liquid undergoes phase transition to solid state. At the melting temperature, a second plateau is observed as the temperature remains unchanged. At temperatures below the melting point, the sample exists as a solid.

So from the curve, the second plateau is observed at around -111 $^{0}C$ . This point represents the phase transition from liquid to solid state.

6 0

3 years ago

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Question 7 of 32

Mice21 [21]

Answer:

The primary type of energy change which occurs by turning on the phone will be the conversion of the stored chemical energy of the battery into electrical energy. The chemical energy is also converted into light energy, sound energy and heat energy. With the passage of time, the energy will be changed back into the chemical energy when we will charge the phone again.

4 0

3 years ago

2Al + 6HCl → 2AlCl3 + 3H2 If the chemical reaction produces 129 grams of AlCl3, how many grams of H2 are also produced?

faust18 [17]

So,

Our conceptual plan is as follows:

g AlCl3 --> mol AlCl3 --> mol H2 --> g H2

$\frac{129g\ AlCl_3}{133.4g/mol}\ *\frac{3mol\ H_2}{2mol\ AlCl_3}\ *2.016g/mol \\ \\=2.92 g\ H_2$

Hope this helps!

5 0

3 years ago

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Select the correct answer from each drop-down menu. At chemical equilibrium, the amount of because .

Elena-2011 [213]

Answer:

The answer that completes the question are in BOLD:

At chemical equilibrium, the amount of PRODUCT AND REACTANT REMAIN CONSTANT because the RATES OF THE FORWARD AND REVERSE REACTIONS ARE EQUAL.

Explanation:

In a reversible chemical reaction, an equilibrium is said to be achieved when the rates of the forward reaction is equal to that of the reverse reaction. A reversible reaction is one in which products are formed from reactants simultaneously with the formation of reactants from products.

The combination of two or more substances called REACTANTS gives rise to another substance called PRODUCT, which can in turn give rise to Reactants again. With time, the rate at which the reactants give rise the products, which is called the FORWARD REACTION will be equal to the rate at which the products give rise to the reactants, which is called REVERSE REACTION. At this point, the chemical reaction is said to be in a STATE OF EQUILIBRIUM.

When the rate at which both reaction occurs becomes equal i.e. at an equilibrium state, the concentration of both the reactants and the products becomes constant i.e. no longer changes. Hence, the amount of the reactants forming the products is the same as the amount of products forming the reactants.

N.B: At chemical equilibrium, the amount of the reactants and products does not necessarily equals zero (0). It simply means that there is no net change in the concentration/amount of both reactants and products.

3 0

4 years ago