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3 years ago

Calcium phosphorus magnesium and fluoride mainly serve as structural components of

1 answer:

5 0

The answer to this question would be: bones and teeth

Bones and teeth are made of calcium and fluoride. This makes the bone and teeth sturdy and able to take much more force. Bones are used to be the body framework and teeth is used to digest food. When the level of calcium in the blood is too low, the calcium from bones can be digested by osteoclast to increase the calcium level in the blood.

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What is the particle theory

kolezko [41]

Answer:

The kinetic theory of matter (particle theory) says that all matter consists of many, very small particles which are constantly moving or in a continual state of motion. The degree to which the particles move is determined by the amount of energy they have and their relationship to other particles.

Six main points of the particle theory:

• All matter is made of particles.

• Particles have space between them.

• Particles are always moving.

• Particles move faster and get farther apart when heated.

• Particles are attracted to each other.

• All Particles of the same substance are identical

7 0

3 years ago

What volume of methanol should be used to make 1.25 L of a 21.0% by volume solution

Marat540 [252]

0.2625 litres is the volume of methanol should be used to make 1.25 L of a 21.0% by volume solution.

Explanation:

Given that:

Volume of solution = 1.25 litres

methanol to be present in the composition of 21% of the volume.

To make 21 % solution by volume of a substance it means that 21 L of the substance is present in 100 L of the solution which is made upto 100 L by adding the solvent.

So, 21 L in 100 L will make 21% solution

x litres of methanol in 1.25 L of solution

So, $\frac{21}{100}$ = $\frac{x}{1.25}$

x = 0.2625 litres

hence, 0.2625 litres of the methanol will be added and the volume will be made to 1.25 litres so that 21% solution by volume gets form.

4 0

3 years ago

What are acids and bases ?

bekas [8.4K]

In chemistry, bases release a hydroxide ion into water, whereas an acid is a compound that gives hydrogen ions to another compound.

8 0

4 years ago

If the atmospheric pressure in the laboratory is 1.2 atm, how many moles of gas were in each syringe? (Hint: Choose one volume a

Naily [24]

Answer:

A: 2.525 x 10-4 mol

B: 2.583 x 10-4 mol

Explanation:

Part A:

Data Given:

. Temperature of water (H2O) = 21.3°C

Convert Temperature to Kelvin

T = °C + 273

T = 21.3 + 273 = 294.3 K

volume of (H2O) gaseous state = 5.1 mL

Convert mL to liter

1000 mL = 1L

5.1 ml = 5.1/1000 = 0.0051 L

Pressure = 1.2 atm

. no. of moles = ?

Solution

no. of moles can be calculated by using ideal gas formula

PV = nRT

Rearrange the equation for no. of moles

n=PV/RT......... (1)

where

P = pressure

V = Volume

T= Temperature

n = Number of moles

R = ideal gas constant

where

R = 0.08206 L.atm/ mol. K

Now put the value in formula (1) to calculate no. of moles of

n = 1.2 atm x 0.0051 L / 0.08206 L.atm.mol-1. K-1 x 294.3 K

n = 0.0061 atm.L / 24.162 L.atm.mol-1

n = 2.525 x 10-4 mol

no. of moles of gas (H2O) = 2.525 x 10-4 mol

Part B:

Data Given:

Temperature of water (H2) = 21.3°C

Convert Temperature to Kelvin

T = "C + 273

T= 21.3 + 273 = 294.3 K

volume of (H2) gas = 5.2 mL

Convert mL to liter

1000 mL = 1 L

5.2 ml = 5.2/1000 = 0.0052 L

Pressure = 1.2 atm

. no. of moles = ?

Solution

no. of moles can be calculated by using ideal gas formula

PV = nRT

Rearrange the equation for no. of moles

n= PV / RT......... (1)

where

P = pressure

V = Volume

T= Temperature

n = Number of moles

R = ideal gas constant

where

R = 0.08206 L.atm/mol. K

Now put the value in formula (1) to calculate no. of moles of

n = 1.2 atm x 0.0052 L/0.08206 L.atm.mol-1. K-1 x 294.3 K

n = 0.0062 atm.L/ 24.162 L.atm.mol-1

n = 2.583 x 10-4 mol

no. of moles of gas (H2) = 2.583 x 10-4 mol

8 0

4 years ago

Ethanol is added to gasoline because the oxygen it contains improves gasoline's burning efficiency. Its combustion reaction is g

Angelina_Jolie [31]

Answer:

A) Exothermic

B) (1) -410.5 kJ (2) -98.1 kcal

C) -976.44 kJ

Explanation:

A) By the value of ΔH (-1236 kJ), we can see that it's negative, it means that the heat is being lost by the reaction, and, because of that, the reaction is exothermic.

B) The molar mass of ethanol is 46.07 g/mol, so, at 15.3 grams, the number of moles is:

n = mass/molar mass

n = 15.3/46.07

n = 0.3321 mol

By the equation

1 mol of ethanol ----------------------- -1236 kJ

0.3321 mol of ethanol ----------------------- x

By a simple direct three rule:

x = -410.5 kJ

1 kJ --------------- 0.2390 kcal

-410 kJ ---------- y

y = -98.10 kcal

C) The molar mass of water is 18 g/mol, so the number of moles at 42.7 g is:

n = 42.7/18

n = 2.37 moles

By the equation

3 moles of water ----------------------- -1236 kJ

2.37 moles of water --------------------- x

By a simple direct three rule:

3x = -2929.32

x = -976.44 kJ

5 0

3 years ago