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3 years ago

A substance made of two or more elements that have been chemically combined is a(n) ______.

Chemistry

2 answers:

RideAnS [48]3 years ago

5 0

Compound (for example: H2O)

Anvisha [2.4K]3 years ago

3 0

Answer: Compound

Explanation:

Element is a pure substance which is composed of atoms of similar elements. Example: $Fe$

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass. Example: $CaCO_3$

Mixtures are heterogeneous materials as they do not have uniform composition and the components are not evenly distributed throughout the material. Example: Sugar solution

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Like all equilibrium constants, Kw varies somewhat with temperature. Given that Kw is 3.31 × 10−13 at some temperature, compute

Artyom0805 [142]

Since Kw= [H⁺][OH⁻], and the concentration of both substances are the same, the equation is now Kw=[H⁺]²
So,
3.31x10⁻¹³ = [H⁺]²
Take the square root= 5.75x10⁻⁷
Then take the negative log to find the pH:
-log(5.75x10⁻⁷) = 6.25

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3 years ago

What is the mass of one gram of calcium?

Anvisha [2.4K]

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Explanation:

The mass of one atom of calcium is the same as the molar mass of the calcium. Also, the atomic mass of calcium is 40.078 g/mol.

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2 years ago

A155-g sample of a unknown substance was heated from 25.0°C to 40.0°C.In the process, the substance absorbed 5696 J of energy. W

Iteru [2.4K]

The answer is: (5696 J) / (155 g) / (40.0 - 25.0)°C = 2.45 J/g·°C

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3 years ago

How many liters of a 0.30M solution are needed to give 2.7 moles of solute? Your answer:

OverLord2011 [107]

You HAVE TO know that molarity (M) tells you the number of moles of a solute per Liters of solution.
M=mol/L
0.3M = 2.7 mol/ Volume
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3 years ago

Read 2 more answers

4.One rubber tire can generate about250,000 BTUS (1BTU=.0003KW ) when it is burned. The average American home consumes about 10,

jekas [21]

Answer:

The number of tires required to power ten homes for one year is approximately 2,730 tires

Explanation:

The given information are;

The energy generated by burning one rubber tire = 250,000 BTUs

1 BTU = 0.0003 kW

The amount of energy consumed by the average American home = 10,000 kWh

Therefore, the amount of energy generated by burning one tire in kW can be found as follows;

The energy generated by burning one rubber tire = 250,000 BTUs

1 BTU = 0.0003 kW

∴ 1 BTU × 250,000 = 250,000 BTUs = 0.0003 kW × 250,000 = 75 kW

We note that 250,000 BTUs is equivalent to 263764 kJ

1 kWh is equivalent to 3600 kJ

10,000 kWh = 10,000 × 3600 = 36,000,000 kJ

The energy requirement for ten homes for one year = 10 × 36,000,000 kJ = 360,000,000 kJ

At 50% efficiency, the energy produced per tire = 0.5 × 263764 kJ = 131,882 kJ

The electrical energy produced per tire = 131,882 kJ/tire

The number of tires required to power ten homes for one year = 360,000,000 kJ/ 131,882 kJ/tire = 2,729.71293 ≈2,730 tires

The number of tires required to power ten homes ≈2,730 tires.

8 0

3 years ago