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2 years ago

Who arranged the elements according to atomic mass and used the arrangement to predict the properties of missing element?

Chemistry

1 answer:

Marina CMI [18]2 years ago

3 0

Answer:

Dmitri Mendeleev

Explanation:

Dmitri Mendeleev a Russian Chemist arranged elements on the periodic table according to their atomic mass. He used this arrangement to predict some of the properties of the missing element.

Dmitri Mendeleev around 1869 described the periodic table.
The table was based on the periodic law which states that "chemical properties of elements are a periodic function of their atomic weights".
In the Mendeleev table, elements are arranged by atomic weights with recurring properties in a periodic manner.

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Mashutka [201]

Answer: i think the best bet i can give you is Option C (2:3)

Explanation: i apologize i haven't done chem in 2 years

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2 years ago

What is the oxidation state of cl in hclo4?

Irina-Kira [14]

There is 1 H atom: (1)(+1) = +1 The oxidation number of O is -2. There are 4 O atoms here: (4)(-2) = -8 So the oxidation state of Cl is +7.

NOTE: The maximum positive oxidation number for chlorine is +7,<span> the same as its group number (VII).</span>

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3 years ago

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Thermal energy is __________.

Gekata [30.6K]

Answer:

Thermal energy (also called heat energy) is produced when a rise in temperature causes atoms and molecules to move faster and collide with each other. The energy that comes from the temperature of the heated substance is called thermal energy.

Credit:

https://www.solarschools.net/knowledge-bank/energy/types/thermal

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3 years ago

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A 50.00 g sample of an unknown metal is heated to 45.00°C. It is then placed in a coffee-cup calorimeter filled with water. The

V125BC [204]

Taking into account the definition of calorimetry, the specific heat of metal is 0.165 $\frac{cal}{gC}$ .

<h3>Definition of calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where:

Q is the heat exchanged by a body of mass m.
C is the specific heat substance.
ΔT is the temperature variation.

<h3>Specific heat capacity of the metal</h3>

In this case, you know:

For metal:

Mass of metal = 50 g
Initial temperature of metal= 45 °C
Final temperature of metal= 11.08 ºC
Specific heat of metal= ?

For water:

Mass of water = 250 g
Initial temperature of water= 10 ºC
Final temperature of water= 11.08 ºC
Specific heat of water = 1.035 $\frac{cal}{gC}$

Replacing in the expression to calculate heat exchanges:

For metal: Qmetal= Specific heat of metal× 50 g× (11.08 C - 45 C)

For water: Qwater= 1.035 $\frac{cal}{gC}$ × 250 g× (11.08 C - 10 C)

If two isolated bodies or systems exchange energy in the form of heat, the quantity received by one of them is equal to the quantity transferred by the other body. That is, the total energy exchanged remains constant, it is conserved.

Then, the heat that the gold gives up will be equal to the heat that the water receives. Therefore:

- Qmetal = + Qwater

- Specific heat of metal× 50 g× (11.08 C - 45 C)= 1.035 $\frac{cal}{gC}$ × 250 g× (11.08 C - 10 C)

Solving:

- Specific heat of metal× 50 g× (-33.92 C)= 1.035 $\frac{cal}{gC}$ × 250 g× 1.08 C

Specific heat of metal× 1696 g×C= 279.45 cal

Specific heat of metal= $\frac{279.45 cal}{1696 gC}$