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3 years ago

The alchemists were the first to do what?

1 answer:

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Alchemists attempted to purify, mature, and perfect certain materials. ... Islamic and European alchemists developed a structure of basic laboratory techniques, theory, terminology, and experimental method, some of which are still in use today.

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How do you draw a bohr diagram for a boron ion?

Otrada [13]

Because Boron likes to lose 3 electrons when it undergoes ionization, we draw a boron ion like a helium atom, with just 2 electrons in the first shell, and 0 in the second

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3 years ago

Read 2 more answers

In order to derive a simplified version of the Nernst equation by assuming standard temperature we can substitute which of the f

Nikitich [7]

Answer:

c. 298 K

Explanation:

Nernst equation is an equation used in electrochemistry that relates the reduction potential of a reaction with the standard potential, temperature and concentrations of the reactants in that are been reducted and oxidized. The formula is:

E = E° - RT / nF ln [Red] / [Ox]

Where R is gas constant (8.314J/molK), T is absolute temperature (In Kelvin), n are moles of electrons and F is faraday constant (K/Volt*mol)

In electrochemistry, standard temperature is taken as 298K. That means by assuming standard temperature we can substitute T as:

5 0

3 years ago

Explain the part that the subduction zones play in the cycling of matter between Earth’s crust and mantle.

WARRIOR [948]

Explanation:

The earth’s crust is broken into separate pieces called tectonic plates (Fig. 7.14). Recall that the crust is the solid, rocky, outer shell of the planet. It is composed of two distinctly different types of material: the less-dense continental crust and the more-dense oceanic crust. Both types of crust rest atop solid, upper mantle material. The upper mantle, in turn, floats on a denser layer of lower mantle that is much like thick molten tar.

Each tectonic plate is free-floating and can move independently. Earthquakes and volcanoes are the direct result of the movement of tectonic plates at fault lines. The term fault is used to describe the boundary between tectonic plates. Most of the earthquakes and volcanoes around the Pacific ocean basin—a pattern known as the “ring of fire”—are due to the movement of tectonic plates in this region. Other observable results of short-term plate movement include the gradual widening of the Great Rift lakes in eastern Africa and the rising of the Himalayan Mountain range. The motion of plates can be described in four general patterns:

Fig 7.15. Diagram of the motion of plates

Collision: when two continental plates are shoved together

Subduction: when one plate plunges beneath another (Fig. 7.15)

Spreading: when two plates are pushed apart (Fig. 7.15)

Transform faulting: when two plates slide past each other (Fig. 7.15)

The rise of the Himalayan Mountain range is due to an ongoing collision of the Indian plate with the Eurasian plate. Earthquakes in California are due to transform fault motion.

Geologists have hypothesized that the movement of tectonic plates is related to convection currents in the earth’s mantle. Convection currents describe the rising, spread, and sinking of gas, liquid, or molten material caused by the application of heat. An example of convection current is shown in Fig. 7.16. Inside a beaker, hot water rises at the point where heat is applied. The hot water moves to the surface, then spreads out and cools. Cooler water sinks to the bottom.

Fig. 7.16. In this diagram of convection currents in a beaker of liquid, the red arrows represent liquid that is heated by the flame and rises to the surface. At the surface, the liquid cools, and sinks back down (blue arrows).

Earth’s solid crust acts as a heat insulator for the hot interior of the planet. Magma is the molten rock below the crust, in the mantle. Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth’s crust.

8 0

3 years ago

Which law states that at constant temperature the pressure of a given amount of gas is inversely proportional to the volume of t

Phantasy [73]

That law is known as Boyle's Law, "The volume of a given mass of a gas is inversely related to pressure when the temperature is constant"

8 0

3 years ago

If 125g of KClO3 is heated, what is the total mass of the products?

Andrej [43]

Given parameters:

Mass of KClO₃ = 125g

Unknown:

Total mass of the products = ?

When KClO₃ is heated, it thermally decomposes to KCl and O₂ according to the chemical equation below;

2KClO₃ → 2KCl + 3O₂

All chemical equations obeys the law of conservation of matter and with this regard, we know that the amount of reactants used is the same as that of the product.

The total mass of the products must give us 125g according to this law of conservation of matter.

Now to find the masses of each product,

Find the number of moles of the given reactant:

Number of moles = $\frac{mass}{molar mass}$

molar mass of KClO₃ = 39 + 35.5 + 3(16) = 122.5g/mol

So number of moles of KClO₃ = $\frac{125}{122.5}$ = 1.02moles

2. Now, using this number of moles, find the number of moles of the products using this value;

2 moles of KClO₃ produced 2 moles of KCl

1.02 moles of KClO₃ will also produce 1.02moles of KCl

2 moles of KClO₃ produced 3 moles of O₂

1.02 moles of KClO₃ will produce $\frac{1.02 x 3} {2}$ mole = 1.53 moles of O₂

3. Now find the masses of each product;

Mass = number of moles x molar mass

molar mass of KCl = 39 + 35.5 = 74.5g/mol

molar mass of O₂ = 16 x 2 = 32g/mol

Mass of KCl = 74.5 x 1.02 = 75.99g

Mass of O₂ = 32 x 1.53 = 48.96g

Total mass of products = mass of KCl + Mass of O₂ = 75.99g + 48.96g

= 124.95g

This value is approximately the same as that of mass of KClO₃

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3 years ago