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2 years ago

An endothermic process is one in which heat is ________ from the surroundings. (2 points)

1 answer:

7 0

The answer is 1) gained
Always think "into" for "endo" (energy goes in), and "exit" for "exo" (energy is released). 

Hope it helps ^-^

You might be interested in

Differentiate between a precipitate and an aqueous solution

antiseptic1488 [7]

Answer:

A precipate is a solid while an aqueous solution is liquid.

Explanation:

A precipitate is a solid which separates after a chemical reaction occurs. It is the solid product of the reaction.

An aqueous solution is formed when a substance is dissolved in water.

6 0

3 years ago

1. Water vapor has_________ energy because it is a __________.

natulia [17]

Water vapor has more energy because it is a gas :)

4 0

3 years ago

An aqueous CsCl solution is 8.00 wt% CsCl and has a density of 1.0643 g/mL at 20°C. What is the boiling point of this solution?

umka2103 [35]

Answer: The boiling point of solution is 100.53

Explanation:

We are given:

8.00 wt % of CsCl

This means that 8.00 grams of CsCl is present in 100 grams of solution

Mass of solvent = (100 - 8) g = 92 grams

The equation used to calculate elevation in boiling point follows:

$\Delta T_b=\text{Boiling point of solution}-\text{Boiling point of pure solution}$

To calculate the elevation in boiling point, we use the equation:

$\Delta T_b=iK_bm$

Or,

$\text{Boiling point of solution}-\text{Boiling point of pure solution}=i\times K_b\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}$

where,

Boiling point of pure solution = 100°C

i = Vant hoff factor = 2 (For CsCl)

$K_b$ = molal boiling point elevation constant = 0.51°C/m

$m_{solute}$ = Given mass of solute (CsCl) = 8.00 g

$M_{solute}$ = Molar mass of solute (CsCl) = 168.4 g/mol

$W_{solvent}$ = Mass of solvent (water) = 92 g

Putting values in above equation, we get:

$\text{Boiling point of solution}-100=2\times 0.51^oC/m\times \frac{8.00\times 1000}{168.4g/mol\times 92}\\\\\text{Boiling point of solution}=100.53^oC$

Hence, the boiling point of solution is 100.53

6 0

3 years ago

Student carries out a titration to determine the concentration of a solution of

Nimfa-mama [501]

The concentration of the Nitric acid solution : 0.114 M

<h3>Further explanation </h3>

Titration is a procedure for determining the concentration of a solution (analyte) by reacting with another solution whose known concentration (usually a standard solution) is called the titrant. Determination of the endpoint/equivalence point of the reaction can use indicators according to the appropriate pH range

Titrations can be acid-base titration, depositional titration, and redox titration. An acid-base titration is the principle of neutralization of acids and bases

Reaction

HNO₃ + NaOH → NaNO₃ + H₂O

Concentration a standard solution of sodium hydroxide : 0.0998 mol/dm³ , and the volume = 25 cm³

moles NaOH=

$\tt mol=M\times V\\\\mol=0.0998\times 25\\\\mol=2.495~mlmoles$

From the equation, mol ratio HNO₃ : NaOH = 1 : 1, so mol HNO₃ = mol NaOH=2.495 mlmoles

The volume of HNO₃ = 21.8 cm³, so the concentration :

$\tt M=\dfrac{n}{V}\\\\M=\dfrac{2.495}{21.8}\\\\M=0.114$

7 0

2 years ago

Which substance would evaporate the fastest at room temperature? (Assume each substance has approximately the same molecular

lutik1710 [3]

Answer:

A non-polar liquid.

Explanation:

Whether a substance dissolves quickly or not depends on how strongly the molecules (or atoms of an element) of a substance are attracted to one another. These interactions between atoms and/or molecules are called intermolecular forces, or IMFs for short. There are several different ones, and these are distinguished from intramolecular forces which are the bonds holding atoms in the molecule together. Attached is a nice little summary of these forces to consider. Our decision lies within the fact that we must pick the substance that experiences the strongest IMF (the one with the most energy). As it turns out, a dipole in a molecule confers some charge distribution on the molecule which makes slightly positive and negative ends. These can attract each other, and it's called dipole-dipole interactions. It can technically happen in a mixture, but let's assume we're dealing with pure substances. Dipoles can only form in polar compounds however, so a non-polar liquid (which is composed of non-polar molecules), will lack these dipoles and therefore cannot form dipole-dipole interactions between the molecules. This results in only having something called dispersion forces (which really every molecule attraction has - so this is the only one). It is very weak, and since the attraction between these molecules is weak, they will tend to come apart, and evaporate. You can think of the IMFs like glue, and a weak glue will not hold the molecules together well, and they will evaporate away.

On the other hand, polar (from dipole interactions) compounds can have general dipole-dipole interactions or hydrogen-bonding interactions (which is a special type of dipole-dipole interaction). H-bonding requires a Hydrogen bonded to either a Nitrogen, Oxygen, or Fluorine to do this. The main thing, is the non-polar ones don't have a dipole, and so they can't form a good intermolecular bond and evaporate quickly.

Water can H-bond, which is why it takes so long to dry and for it to evaporate in general. Nail polish, which is really a solution of acetone, has considerably weaker dipole-dipole bonds (compared to H-bonds), and evaporates quicker than water. Hope this helps!

Note: Figure taken from Chemistry: The Molecular Nature of Matter and Change 8th edition.

3 0

2 years ago