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3 years ago

What are some natural measures of time

Chemistry

1 answer:

Len [333]3 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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(b) Data has been collected to show that at a given wavelength in a 1 cm pathlength cell, Beer's Law for the absorbance of Co2+

OlgaM077 [116]

Answer : The concentration of a solution with an absorbance of 0.460 is, 0.177 M

Explanation :

Using Beer-Lambert's law :

$A=\epsilon \times C\times l$

where,

A = absorbance of solution

C = concentration of solution

l = path length

$\epsilon$ = molar absorptivity coefficient

From this we conclude that absorbance of solution is directly proportional to the concentration of solution at constant path length.

Thus, the relation between absorbance and concentration of solution will be:

$\frac{A_1}{A_2}=\frac{C_1}{C_2}$

Given:

$A_1$ = 0.350

$A_2$ = 0.460

$C_1$ = 0.135 M

$C_2$ = ?

Now put all the given values in the above formula, we get:

$\frac{0.350}{0.460}=\frac{0.135}{C_2}$

$C_1=0.177M$

Therefore, the concentration of a solution with an absorbance of 0.460 is, 0.177 M

3 0

3 years ago

A eudiometer contains a 65.0 ml sample of a gas collected

SCORPION-xisa [38]

Answer:

53.1 mL

Explanation:

Let's assume an ideal gas, and at the Standard Temperature and Pressure are equal to 273 K and 101.325 kPa.

For the ideal gas law:

P1*V1/T1 = P2*V2/T2

Where P is the pressure, V is the volume, T is temperature, 1 is the initial state and 2 the final state.

At the eudiometer, there is a mixture between the gas and the water vapor, thus, the total pressure is the sum of the partial pressure of the components. The pressure of the gas is:

P1 = 92.5 - 2.8 = 89.7 kPa

T1 = 23°C + 273 = 296 K

89.7*65/296 = 101.325*V2/273

101.325V2 = 5377.45

V2 = 53.1 mL

6 0

3 years ago

How many moles of LiOH are needed to react completely with 25.5 g of CO2

LekaFEV [45]

Answer:

3.18 mol

Explanation:

$2LiOH+CO_{2}-> Li_{2}CO_{3} +H_{2}O$

n(CO2) = mass/ Mr.

= 25.5 / 16

= 1.59 mol

As per the equation above,

n(LiOH) : n(CO2)

2 : 1

∴ 3.18 : 1.59

3 0

3 years ago

2. Water is an example of a(n)

Alexus [3.1K]

it would be A ,inorganic Compound

6 0

3 years ago

What are the compounds empirical and molecular formulas

Liono4ka [1.6K]

Answer:

The empirical formula is the simplest ratio of atoms while molecular is the actual formula.

Explanation:

Empirical Formula is the simplest ratio of atoms present in the compound.

The molecular formula shows the actual number of atoms present in the compound.

For example, CH is the empirical formula and C6H6 is the molecular formula of benzene.

5 0

2 years ago