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iVinArrow [24]
2 years ago
8

A laboratory technician needs to prepare 500 milliliters of a 2 M solution of sodium hydroxide (NaOH) in a flask. The flask has

a volume of exactly 500 milliliters. Which quantity does the laboratory technician need to measure before making the solution?
A. the mass of the solute

B. the mass of the solvent

C. the mass of the solution

D. the mass of the flask
Chemistry
1 answer:
Phantasy [73]2 years ago
7 0

The correct answer is option A, that is, the mass of the solute.  

Before, preparing the solution, the laboratory technician needs to measure the mass of the solute. In the given question, the molarity of NaOH is given, the volume of the solution is given, the molar mass of NaOH is 40 g/mol.  

As one knows the molarity of the solute, the volume of the solution, and the molar mass of the solute, thus, there is a need to determine only the mass of the solute prior of preparing the solution.  


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The potential energy diagram for a reaction starts at 180 kJ and ends at 300 kJ. What type of reaction does the diagram best rep
aleksklad [387]

Answer: Endothermic reaction

Explanation:

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and \Delta H for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and \Delta H for the reaction comes out to be positive.

As the energy of reactants is 180 kJ and that of products is 300 kJ, the energy of products is greater than that of reactants, which means  the energy has been absorbed and reaction is endothermic.

8 0
2 years ago
The combustion of propane gas is used to fuel barbeque grills. If 4.65 moles of propane, C3H8, are burned in a grilling session,
Varvara68 [4.7K]

Answer:

<h3>moles of carbon dioxide=13.95mol</h3>

Explanation:

First wrie down the balance chemical reaction:

C_3H_8(g) + 5 O_2(g) \rightarrow 3 CO_2(g) + 4 H_2O(l)

Combustion reaction: The reacion in which hydrocarbon is burnt in the presence of oxygen gas and it releases heat and this reaction exothermic because heat of cumbustion is negative.

eg. burning of methane

By using unitry method,

From the above balanced reaction it is clearly that,

from 1 mole of propane 3 moles of carbon dioxide is formed

there fore,

from 4.65 mole of propane 3 \times 4.65 moles of carbon dioxide will form

moles of carbon dioxide=13.95mol

8 0
2 years ago
Using the mass of the proton 1.0073 amu and assuming its diameter is 1.0×10−15m, calculate the density of a proton in g/cm3.
icang [17]

Answer : 3.2 X 10^{15} g/cm^{3}

Explanation :  To convert amu i.e. atomic mass unit in grams we have the conversion factor as 1 amu = 1.66054 X 10^{-24} g

we know the mass of the proton is 1.0073 amu

So converting it into grams we have to multiply;

1.0073 amu X  1.66054 X 10^{-24} g/amu = 1.673 X 10^{-24} g

Now, Volume = 1/6πd³ as diameter is given as 1.0 X 10^{-15} m converting it to cm will require to multiply with 100

∴ Volume  = 1/6π (1.0 X 10^{-15}mX 100 cm / 1 m)^{3}

Hence, volume =  5.236 X 10^{-40} cm^{3}

Therefore, Density = mass / volume

∴ Density =  1.673 X 10^{-24} g / 5.236 X 10^{-40} cm^{3}

Therefore, Density will be 3.2 X 10^{15} g/cm^{3}.

6 0
2 years ago
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Increased motion in the particles in a liquid allows the particles to
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Particles in a liquid are more loosely packed there for they have more room to move and can flow around eachother . Hope this helps XD
8 0
2 years ago
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How would each of the following procedural errors affect the results to be expected in this experiment? Give your reasoning in e
Digiron [165]

Answer:

a) if the liquid is not vaporized completely, then the condensed vapor in the flask contains the air which is initially occupied before the liquid is heated. When calculating the molar mass of the vapor the moles of air which are initially present are not excluded, so that the molar mass of the vapor would be an increase in value.

b) While weighing the condensed vapor, the flask should be dried. If the weighing flask is not dried then the water which is layered on the surface of the flask is also added to the mass of the vapor. Therefore, the mass of the vapor that is calculated would be increase.

c) When condensing the vapor, the stopper should not be removed from the flask, because the vapor will escape from the flask and a small amount of vapor will condense in the flask. Therefore, the mass of the condensed vapor would be In small value.

d) If all the liquid is vaporized, when the flask is removed before the vapor had reached the temperature of boiling water, then the boiling

temperature of that liquid would be lower than that of the boiling temperature of the water.Therefore, the liquid may have more volatility.

7 0
2 years ago
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