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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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37.5g of nitrogen reacts with 15.5 g of hydrogen. What mass of ammonia can be made? What is the limiting reactant?

Gennadij [26K]

Answer:

Limiting reactants or limiting reagents decide the amount of product formed and the amount of excess reagent used.

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3 years ago

Identifica los dos pares conjugados acido-base en cada una de las siguientes reacciones

aliya0001 [1]

Answer:

PULLIN OUT THE COUPE AT THE LOT?

Explanation:

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3 years ago

What two types of matter are closest in<br> density? How do you know?<br> ings.

maks197457 [2]

Answer:

Density: The molecules of a liquid are packed relatively close together. Consequently, liquids are much denser than gases. The density of a liquid is typically about the same as the density of the solid state of the substance.

In a gas, the distance between molecules, whether monatomic or polyatomic, is very large compared with the size of the molecules; thus gases have a low density and are highly compressible. In contrast, the molecules in liquids are very close together, with essentially no empty space between them

I hope it helps you

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3 years ago

Draw the resonance structures for the conjugate base of Phenol (C6H6O). In one sentence, explain why phenol (C6H6O) has a pKa of

notsponge [240]

Answer:

The four resonance structures of the phenoxide ion are shown in the image attached

The conjugate base of cyclohexanol has only one resonance contributor, while

the conjugate base of phenol has four resonance contributors.

Explanation:

In organic chemistry, it is known that structures are more stable if they possess more resonance contributors. The greater the number of contributing canonical structures, the more stable the organic specie. Since the phenoxide ion has four contributing canonical structures, it is quite much more stable than cyclohexanol having only one contributing structure to its conjugate base. Hence the PKa(acid dissociation constant) of phenol is lesser than that of cyclohexanol. The conjugate base of phenol is stabilized by resonance.

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3 years ago

If 18.7ml of 0.01500M aqueous HCl is required to titrâtes 15.00ml of an aqueous solution of NaOH to the equivalence point, what

sweet [91]

Answer:

0.0187 M

Explanation:

Step 1: Write the balanced neutralization reaction

NaOH + HCl ⇒ NaCl + H₂O

Step 2: Calculate the reacting moles of HCl

18.7 mL of 0.01500 M HCl react.

0.0187 L × 0.01500 mol/L = 2.81 × 10⁻⁴ mol

Step 3: Calculate the reacting moles of NaOH

The molar ratio of HCl to NaOH is 1:1. The reacting moles of NaOH are 1/1 × 2.81 × 10⁻⁴ mol = 2.81 × 10⁻⁴ mol.

Step 4: Calculate the molarity of NaOH

2.81 × 10⁻⁴ moles are in 15.00 mL of NaOH.

[NaOH] = 2.81 × 10⁻⁴ mol/0.01500 L = 0.0187 M

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3 years ago