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vitfil [10]
3 years ago
15

FOR FUTURE FLVS STUDENT

Chemistry
1 answer:
dalvyx [7]3 years ago
6 0
<h3>Answers: </h3><h2>1. (D) 30°C </h2>

A good example that most people are familiar with is the heating of water. If we take a beaker packed with ice (solid water) and put in on a hot plate that has a temperature of 120 ° C we all know what will happen. First, the ice will dissolve to liquid water. Then the water will rise in temperature. Then ultimately the water will boil. During this complete process, the temperature of the hot plate will be greater than the temperature of the beaker of water. Thus, during this whole process energy will move in the form of heat from the hot plate into the water.  


<h2>2. (C) Boiling </h2>

When a system comprises only one phase (solid, liquid or gas), the temperature will rise when it gets energy. The rate of temperature rise will be dependent on the heat capacity of the phase in the system. When the heat capacity is high, the temperature rises slowly because much energy is needed to increase its temperature by one degree. Thus, the slope of temperature rise for the solid, liquid, and gases varies.  

<h2 /><h2>3. (C) Liquid </h2>

A cooling curve is a line graph that describes the difference of phase of matter, typically from a gas to a solid or a liquid to a solid. The independent variable is time and the dependent variable is temperature. The original point of the graph is the starting temperature of the matter,  regarded as the "pouring temperature".


<h2>4. Only the motion and arrangement of the particles changes, not the identity of the substance.</h2>

Water is held together by hydrogen bonds, the soundest of inter-molecular forces. This is where a hydrogen atom in one molecule is completely attracted to an electronegative atom (in this case, oxygen) in the other. When sufficient energy is absorbed by H2O, the molecules vibrate so vigorously that these bonds are loosened, giving them scope to bounce around. When this energy is taken out of the H2O, this transmits room for hydrogen bonds to tighten, squeezing collectively to form a solid.


<h2>5. liquid iron (2,000°C)</h2>

The kinetic energy of an object is the energy that it controls due to its motion. It is described as the work needed to stimulate a body of a given mass from rest to its stated velocity. Having obtained this energy during its acceleration, the body keeps this kinetic energy unless its speed changes.


<h2>6.</h2>

Boiling is the method by which a liquid changes into a vapour when it is burned to its boiling point. The transition from a liquid phase to a gaseous phase happens when the vapour pressure of the liquid is similar to the atmospheric pressure used on the liquid. Boiling is a physical change in which molecules are not chemically altered during the process. When atoms or molecules of a liquid are ready to expand out enough to change from a liquid phase to a gaseous phase, bubbles form and boiling occurs


<h2>7. (C) It will expand because the helium atoms will move more quickly and get farther apart.</h2>

Over a period of centuries and through various experiments, physicists and chemists have been equipped to describe key characteristics of a gas, including the volume it controls (V) and the pressure it exerts on its enclosure (P), to temperature (T).


<h2>8. (C) Neon Gas</h2>

Neon is a colourless, odourless, inert monatomic gas under regular conditions, with about two-thirds the density of air. It was recognized as one of the three residual rare inert elements surviving in the dry air after nitrogen, oxygen, argon and carbon dioxide were evacuated. Neon was the second of these three rare gases to be found and was immediately identified as a new element from its bright red emission spectrum.

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A certain substance X has a normal freezing point of 5.6 °C and a molal freezing point depression constant Kf-7.78 °C-kg·mol-1.
Harrizon [31]

Answer:

27.60 g urea

Explanation:

The <em>freezing-point depression</em> is expressed by the formula:

  • ΔT= Kf * m

In this case,

  • ΔT = 5.6 - (-0.9) = 6.5 °C
  • Kf = 7.78 °C kg·mol⁻¹

m is the molality of the urea solution in X (mol urea/kg of X)

First we<u> calculate the molality</u>:

  • 6.5 °C = 7.78 °C kg·mol⁻¹ * m
  • m = 0.84 m

Now we<u> calculate the moles of ure</u>a that were dissolved:

550 g X ⇒ 550 / 1000 = 0.550 kg X

  • 0.84 m = mol Urea / 0.550 kg X
  • mol Urea = 0.46 mol

Finally we <u>calculate the mass of urea</u>, using its molecular weight:

  • 0.46 mol * 60.06 g/mol = 27.60 g urea

7 0
3 years ago
A sample of CO2 gas has a volume of 2.7 L at 78.5 kPa. At what pressure would this sample of gas have a volume of 4.0L? Temperat
lisabon 2012 [21]

Answer:

52.99 kPa

Explanation:

Initial volume V1 = 2.7 L

Initial Pressure P1 = 78.5 kPa

Final Volume V2 = 4.0L

Final Pressure P2 = ?

Temperature is constant

The relationship between these quantities is given by the mathematical expression of Boyles law. This is given as;

V1P1 = V2P2

P2 = V1P1 / V2

P2 = 2.7 * 78.5 /  4.0

P2 = 52.99 kPa

7 0
3 years ago
How many molecules of ammonia (NH3) are contained in 10 moles of NH3? Please provide the work if you could :)
nlexa [21]
<span>Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We do as follows:

 </span>10 mol NH3 ( 6.022 x 10^23 molecules / 1 mol ) = 6.022x10^24 molecules NH3
3 0
3 years ago
Read 2 more answers
Define critical point. Group of answer choices The temperature and pressure below which a supercritical fluid exists. The temper
attashe74 [19]

Answer:

The temperature and pressure below which a supercritical fluid exists.

Explanation:

Critical point is a region on the phase diagram where fluid phases (liquids and gases) have the equal density.

This is caused by increased temperature and pressure of the fluid particles in a confided container. Supercritical fluids exist in a state above critical point.

I hope this explanation was clear.

8 0
3 years ago
What is missing from the temperature and volume<br> graph shown at right?
Anna11 [10]
X axis hopes this helps
8 0
2 years ago
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