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3 years ago

A scientific theory never changes. ture or false ?

Chemistry

1 answer:

andrezito [222]3 years ago

8 0

Answer:

False.

Explanation:

Scientific theories and hypothesis are all tentative. Science tries to prove something is either true of false and come up with answers (as much as we can) for many problems. Sometimes they are made based on limited data or information. Over the years, we come up with need findings discoveries which are able to give us more information and give us better answers. There have been a couple of scientific laws which had to be completely revised or discarded after new observations. An example of this would be the Laws of Thermodynamics. A couple of the laws have been changed over the decades after scientists made new disoveries and observations.

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Menthol, the substance we can smell in mentholated cough drops, is composed of c, h, and o. a 9.045×10−2 −mg sample of menthol i

Ket [755]

Answer:

Empirical Formula = C₁₀H₂₀O

Solution:

Data Given:

Mass of Menthol = 9.045 × 10⁻² mg = 9.045 × 10⁻⁵ g

Mass of CO₂ = 0.2546 mg = 0.0002546 g

Mass of H₂O = 0.1043 mg = 0.0001043 g

Step 1: Calculate %age of Elements as;

%C = (mass of CO₂ ÷ Mass of sample) × (12 ÷ 44) × 100

%C = (0.0002546 ÷ 9.045 × 10⁻⁵) × (12 ÷ 44) × 100

%C = (2.814) × (12 ÷ 44) × 100

%C = 2.814 × 0.2727 × 100

%C = 76.73 %

%H = (mass of H₂O ÷ Mass of sample) × (2.02 ÷ 18.02) × 100

%H = (0.0001043 ÷ 9.045 × 10⁻⁵) × (2.02 ÷ 18.02) × 100

%H = (1.153) × (2.02 ÷ 18.02) × 100

%H = 1.153 × 0.1120 × 100

%H = 12.91 %

%O = 100% - (%C + %H)

%O = 100% - (76.73% + 12.91%)

%O = 100% - 89.64%

%O = 10.36 %

Step 2: Calculate Moles of each Element;

Moles of C = %C ÷ At.Mass of C

Moles of C = 76.73 ÷ 12.01

Moles of C = 6.3888 mol

Moles of H = %H ÷ At.Mass of H

Moles of H = 12.91 ÷ 1.01

Moles of H = 12.7821 mol

Moles of O = %O ÷ At.Mass of O

Moles of O = 10.36 ÷ 16.0

Moles of O = 0.6475 mol

Step 3: Find out mole ratio and simplify it;

C H O

6.3888 12.7821 0.6475

6.3888/0.6475 12.7821/0.6475 0.6475/0.6475

9.86 19.74 1

≈ 10 ≈ 20 1

Result:

Empirical Formula = C₁₀H₂₀O₁

8 0

4 years ago

Explain examples of a physical and chemical change of matter

monitta

HEY DEAR..

PHYSICAL CHANGE

Those Changes in which no new substances are formed are called physical changes. it is a temporary changes which can be reversed easily to form the original substance.

Example:- Melting of ice , Making a solution, Glowing of an electric bulb , freezing of water etc.

CHEMICAL CHANGE

Those changes in which new substances are formed are called chemical changes. it means it is permanent changes which are usually irreversible.

Example:- Burning of charcoal, fuels and cutting of trees, even digestion of food is in chemical change.

HOPE ITS HELPFULLL

BE BRAINLY.

6 0

4 years ago

The sidewalk outside is covered in ice what kind of shoes should i wear to walk on the ice explane

babunello [35]

Answer:

Well you should wear boots.

Explanation:

Boots because most winterized boots have tread on the bottom, allowing you to grip the ice better. They will help prevent you from slipping , and are even good for walking up slippery hills.

4 0

3 years ago

A 35 L tank of oxygen is at 315 K with an internal pressure of 190 atmospheres. How

nata0808 [166]

Answer:

600.7 moles

Explanation:

Applying,

PV = nRT................... Equation 1

Where P = Pressure of oxygen, V = Volume of oxygen, n = number of moles, R = molar gas constant, T = Temperature.

make n the subject of the equation

n = PV/RT............... Equation 2