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3 years ago

What were the first 16 elements known in 1760

2 answers:

4 0

The discovery of the first basic elements in nature was sufficient to begin the era of industrial revolution through combining two or more of these elements in order to speed up the production processes.

The first discovered elements in nature were:
sulphur
chlorine
argon
neon
carbon
oxygen
helium
silicon
calcium
hydrogen
nitrogen
sodium
fluorine
lithium
aluminum

Volgvan3 years ago

4 0

This is a simple matter of looking up the discovery date of the elements. And the results are Known since ancient times Copper, Sulfur, Silver, Tin, Antimony, Gold, Mercury, Lead Then somewhere around 1400, Bismuth. 1669 Phosphorus 1694 Carbon 1735 Iron 1735 Platinum 1751 Nickel, Cobalt 1755 Magnesium The list in alphabetical order is: Antimony, Bismuth, Carbon, Cobalt, Copper, Gold, Iron, Lead, Magnesium, Mercury, Nickel, Phosphorus, Platinum, Silver, Sulfur, and Tin

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If the temperature of 15 grams of water changes from 21C to 24C, how many joules of heat were involved? Show work

goblinko [34]

Answer:

189 Joules

Explanation:

Applying,

Q = cm(t₂-t₁)............. equation 1

Where Q = Heat, c = specific heat capacity of water, m = mass of water, t₁ = Initial Temperature, t₂ = Final temperature.

From the question,

Given: m = 15 grams = 0.015 kg, t₁ = 21 °C, t₂ = 24 °C

Constant: c = 4200J/kg.°C

Substitute these values into equation 1

Q = 0.015×4200×(24-21)

Q = 0.015×4200×3

Q = 189 Joules

6 0

3 years ago

A solution is prepared by adding 100 mL of 1.0 M HC₂H₃O₂(aq) to 100 mL of 1.0 M NaC₂H₃O₂(aq). The solution is stirred and its pH

anastassius [24]

Answer: Option (c) is the correct answer.

Explanation:

When an acid or base is added to a solution then any resistance by the solution in changing the pH of the solution is known as a buffer.

This is because a buffer has the ability to not get affected by the addition of small amounts of an acid or a base. As a result, it helps in maintaining the pH of the solution.

In the give case, when we add the HCl then more number of protons will dissociate. This causes the acetate to react with the protons and leads to the formation of acetic acid.

We know that acetic acid is a weak acid and it dissociates partially or feebly. Therefore, no change in pH will take place.

Thus, we can conclude that equation $H_{3}O^{+}(aq) + C_{2}H_{3}O^{-}_{2}(aq) \rightarrow HC_{2}H_{3}O_{2}(aq) + H_{2}O(l)$ represents the chemical reaction that accounts for the fact that acid was added but there was no detectable change in pH.

3 0

3 years ago

Which element and how many atoms does each compound have in the picture?

Stells [14]

The first one has 35 atoms and the elements hydrogen, oxygen and chlorine

The second one has 9 atoms and the elements sodium, carbon, and helium

7 0

3 years ago

Calculate the freezing point of a solution containing 5.0 grams of KCl and 550.0 grams of water. The molal-freezing-point-depres

yulyashka [42]

Answer: The freezing point of solution is -0.454°C

Explanation:

Depression in freezing point is defined as the difference in the freezing point of pure solution and freezing point of solution.

The equation used to calculate depression in freezing point follows:

$\Delta T_f=\text{Freezing point of pure solution}-\text{Freezing point of solution}$

To calculate the depression in freezing point, we use the equation:

$\Delta T_f=iK_fm$

Or,

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

where,

Freezing point of pure solution = 0°C

i = Vant hoff factor = 2

$K_f$ = molal freezing point elevation constant = 1.86°C/m

$m_{solute}$ = Given mass of solute (KCl) = 5.0 g

$M_{solute}$ = Molar mass of solute (KCl) = 74.55 g/mol

$W_{solvent}$ = Mass of solvent (water) = 550.0 g

Putting values in above equation, we get:

$0-\text{Freezing point of solution}=2\times 1.86^oC/m\times \frac{5\times 1000}{74.55g/mol\times 550}\\\\\text{Freezing point of solution}=-0.454^oC$

Hence, the freezing point of solution is -0.454°C

3 0

3 years ago

¿Qué es un orbital s, un orbital p, un orbital d, un orbital f y cómo se representa cada uno?

irina1246 [14]

Answer:

Cada uno de esos orbitals sons los differentes grupos en la tabla periodica.

Explanation:

3 0

3 years ago

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