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Flura [38]
4 years ago
9

What are some natural measures of time

Chemistry
1 answer:
Len [333]4 years ago
7 0

most events like the rising and setting of the Sun were used a natural measurement of time until recently.

Solar time, which is based on the motion of the Sun, is not the only way of measuring time, however. One might keep track of the regular appearance of the full Moon. That event occurs once about every 29.5 solar days. The time between appearances of new moons, then, could be used to define a month.

One also can use the position of the stars for measuring time. The system is the same as that used for the Sun, since the Sun itself is a star. All other stars also rise and set on a regular basis.

Although any one of these systems is a satisfactory method for measuring some unit of time, such as a day or a month, the systems may conflict with each other. It is not possible, for example, to fit 365 solar days into 12 or 13 lunar months exactly. This problem creates the need for leap years

Read more: http://www.scienceclarified.com/Ti-Vi/Time.html#ixzz5e1E705sr

I abbreviated most of it but there is a ton more at this link if you still need more.

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When heat energy is removed, two changes are observed:
harkovskaia [24]

Answer: Option (A) is the correct answer.

Explanation:

Condensation is defined as the process in which vapors or gaseous phase changes into liquid phase.

Freezing is the process in which liquid phase changes into solid phase.

Evaporation is the process in which liquid phase changes into vapors or gaseous phase.

Melting is the process in which solid phase changes into liquid phase.

Therefore, we can conclude that names for given phase changes A and B is that A is condensation and B is freezing.

3 0
4 years ago
Read 2 more answers
Animals use oxygen in the process of <br> blank<br> and emit CO2 as a byproduct.
Temka [501]

Answer:

Respiration

Explanation:

The act of breathing, simple as that!

Hope this helped!!

4 0
2 years ago
I begin the reaction with 0.45 g of beryllium. If my actual yield of beryllium chloride (mm = 79.91 g/mol) was 3.5 grams, what w
trasher [3.6K]

The percentage of yield was 777.78%

<u>Explanation:</u>

We have the equation,

Be [s]  +  2 HCl [aq]  →  BeCl 2(aq]  + H 2(g]  ↑ Be (s]  + 2 HCl [aq]  →  BeCl 2(aq]  + H 2(g] ↑

To find the percent yield we have the formula

Percentage of Yield= what you actually get/ what you should theoretically get  x 100

                                   =3.5 g/0.45 g 100

                                    = 777.78 %

The percentage of yield was 777.78%

5 0
4 years ago
If you place 1.0 L of ethanol (C2H5OH) in a small laboratory that is 3.0 m long, 2.0 m wide, and 2.0 m high, will all the alcoho
ankoles [38]

If you place 1.0 L of ethanol (C2H5OH) in a small laboratory that is 3.0 m long, 2.0 m wide, and 2.0 m high, will all the alcohol evaporate? If some liquid remains, how much will there be? The vapor pressure of ethyl alcohol at 25 °C is 59 mm Hg, and the density of the liquid at this temperature is 0.785g/cm^3 .

will all the alcohol evaporate? or none at all?

Answer:

Yes, all the ethanol present in the laboratory will evaporate since the mole of ethanol present in vapor is greater. The volume of ethanol left will therefore  be zero.

Explanation:

Given that:

The volume of alcohol which is placed in a small laboratory = 1.0 L

Vapor pressure of ethyl alcohol  at 25 ° C = 59 mmHg

Converting 59 mmHg to atm ; since 1 atm = 760 mmHg;

Then, we have:

= \frac{59}{760}atm

= 0.078 atm

Temperature = 25 ° C

= ( 25 + 273 K)

= 298 K.

Density of the ethanol = 0.785 g/cm³

The volume of laboratory = l × b × h

= 3.0 m × 2.0 m × 2.5 m

= 15 m³

Converting the volume of laboratory to liter;

since 1 m³ = 100 L; Then, we  have:

15 × 1000 = 15,000 L

Using ideal gas equation to determine the moles of ethanol in vapor phase; we have:

PV = nRT

Making n the subject of the formula; we have:

n = \frac{PV}{RT}

n = \frac{0.078 * 15000}{0.082*290}

n = 47. 88 mol of ethanol

Moles of ethanol in 1.0 L bottle can be calculated as follows:

Since  numbers of moles = \frac{mass}{molar mass}

and mass = density × vollume

Then; we can say ;

number of moles = \frac{density*volume }{molar mass of ethanol}

number of moles =\frac{0.785g/cm^3*1000cm^3}{46.07g/mol}

number of moles = \frac{&85}{46.07}

number of moles = 17.039 mol

Thus , all the ethanol present in the laboratory will evaporate since the mole of ethanol present in vapor is greater. The volume of ethanol left will therefore be zero.

5 0
3 years ago
Why are salt and sugar both able to dissolve in water, even though the solutes have different types of chemical bonding? everyth
Bas_tet [7]

Sucrose and other simple sugars may dissolve in water because they are polar molecules with an unequal charge distribution. Water is also quite polar, capable of forming weak, temporary connections with other polar compounds.

Salt dissolves into ions, with Na being positively charged and CL being negatively charged. Because water is highly polar (parts of the molecule are negatively charged while others are positively charged), the sodium ions are surrounded by water molecules, with the negatively charged component of the water molecules surrounding the NA ion. The Cl ion experiences the inverse effect.

<h3>How does salt dissolve in water compared to sugar?</h3>

A solution's solute and solvent are two different types of substances that can dissolve one another. Different solvents have different levels of solubility for different solutes. For instance, sugar is far more soluble in water than salt. Even sugar, though, has a limit on how much may dissolve.

learn more about solubility refer:

brainly.com/question/23946616

#SPJ4

5 0
1 year ago
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