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riadik2000 [5.3K]
3 years ago
9

Provide at least three reasons why friction is needed.

Chemistry
2 answers:
faust18 [17]3 years ago
6 0
Friction occurs when two surfaces come into contact. Excess friction hinders movement, and it wastes energy. Friction refers to a force that opposes motion. It is important because it is applied in almost all life processes.
levacccp [35]3 years ago
4 0
<span>Friction slides or rolls one object to another</span>
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What is the pH of a solution made by mixing 30.00 mL 0.10 M HCl with 40.00 mL of 0.10 M KOH? Assume that the volumes of the solu
nirvana33 [79]

Answer:

pH = 12.15

Explanation:

To determine the pH of the HCl and KOH mixture, we need to know that the reaction is  a neutralization type.

HCl  +  KOH  →  H₂O  +  KCl

We need to determine the moles of each compound

M = mmol / V (mL) → 30 mL . 0.10 M = 3 mmoles of HCl

M = mmol / V (mL) → 40 mL . 0.10 M = 4 mmoles of KOH

The base is in excess, so the HCl will completely react and we would produce the same mmoles of KCl

HCl  +  KOH  →  H₂O  +  KCl

3 m       4 m                       -

             1 m                      3 m

As the KCl is a neutral salt, it does not have any effect on the pH, so the pH will be affected, by the strong base.

1 mmol of KOH has 1 mmol of OH⁻, so the [OH⁻] will be 1 mmol / Tot volume

[OH⁻] 1 mmol / 70 mL = 0.014285 M

- log [OH⁻] = 1.85 → pH = 14 - pOH → 14 - 1.85 = 12.15

3 0
3 years ago
What do greenhouse gases (CO2) do to the atmosphere?
Alborosie

Answer:

they causes climate change by trapping heat and also they contribute to respiratory diseases from smog and air pollution

4 0
3 years ago
Read 2 more answers
Scientist can use trees to look at climates of the past. How? What information can they gather and how do they gather it? Explai
andrezito [222]

Explanation:

Scientist use trees a whole lot to look at climate of the past by examining tree rings.

These are layers of cambium in each successive years formed. They have an annual growth pattern and are known as tree rings.

Tree rings can be used to decipher the age of a tree.

  • These three rings can be used to interpret climatic patterns.
  • During a wet climate, the tree rings are more robust and bigger.
  • In a dry climate, the rings are thinner.
  • These alternating patterns can be used to decipher the climatic signatures in a tree.
  • Sometimes, it is possible to evaluate some certain isotopes that are useful in climatic studies.

learn more:

Climate change brainly.com/question/7824762

#learnwithBrainly

6 0
3 years ago
How many moles are contained in 2.0 L of N2 at standard temperature and pressure.
GuDViN [60]

0.091 moles are contained in 2.0 L of N2 at standard temperature and pressure.

Explanation:

Data given:

volume of the nitrogen gas = 2 litres

Standard temperature = 273 K

Standard pressure = 1 atm

number of moles =?

R (gas constant) = 0.08201 L atm/mole K

Assuming nitrogen to be an ideal gas at STP, we will use Ideal Gas law

PV = nRT

rearranging the  equation to calculate number of moles:

PV = nRT

n = \frac{PV}{RT}

putting the values in the equation:

n = \frac{1X2}{0.08201 X 273}

n = 0.091 moles

0.091 moles of nitrogen gas is contained in a container at STP.

6 0
3 years ago
Why is it better to conduct an experiment more than once?
lilavasa [31]

The first reason to repeat experiments is simply to verify results. Different science disciplines have different criteria for determining what good results are. Biological assays, for example must be done in at least triplicate to generate acceptable data. Science is built on the assumption that published experimental protocols are repeatable.


2)      The next reason to repeat experiments is to develop skills necessary to extend established methods and develop new experiments. “Practice make perfect” is true for the concert hall and the chemical laboratory.


3)      Refining experimental observations is another reason to repeat. Maybe you did not follow the progress of the reaction like you should have.


4)      Another reason to repeat experiments is to study and/or improve them in way. In the synthetic chemistry laboratory, for example, there is always a desire to improve the yield of a synthetic step. Will certain changes in the experimental conditions lead to a better yield? The only way to find out is to try it! The scientific method informs us that it is best to only make one change at a time.


5)  The final reason to repeat an extraction, chromatographic or synthetic protocol is to produce more of your target substance. This is sometimes referred to scale-up.

8 0
3 years ago
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