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Mazyrski [523]
4 years ago
7

________ investigations allow for the control of variables

Chemistry
2 answers:
Hoochie [10]4 years ago
8 0

Continuous investigation of the research is expected so that the control variables specified are not out of the problem boundary

\boxed{\boxed{\bold{Further~explanation}}}

Chemistry is the study of structures, properties, and changes in matter, and the energy that accompanies them

The material structure includes the forming components and their comparisons, the process of forming bonds or combining components/elements forming them

The nature of the material including the changes in physics and chemical changes

The energy produced or needed and where the source includes the quantity.

The development of chemistry begins with experiments that consist of chemical stages/processes. This process is applied in the form of a scientific method that is commonly used by scientists in carrying out experiments.

This scientific method is carried out in several stages:

1. Observation, grouping, describing or distinguishing subjects that will be carried out research

2. Determine the problem, what limits and how the research process will be carried out

2. Data, collect information either directly or through text/book references

3. Hypothesis, taking conclusions from information collected data

4. Experiments, looking for causes, root causes of the subject under study, through a process of experimentation either on a lab or industrial scale

5. Analysis, making images either graphically or table, qualitatively (general symptoms in observed objects such as colors, textures, shapes) quantitatively (measurement data such as area, weight, volume)

6. Conclusion, based on experiments and data, the hypothesis can be rejected or accepted

7. Compilation of laws or theories, hypotheses that have been tested through various experiments can be compiled a theory

Variables, which are objects in the study can be determined in 2:

1.Independent variable, which is a variable that can be changed according to the purpose of the experiment

2. Fixed variable, i.e. variable whose value is constant and observed to determine changes in independent variables

We can control the independent variables according to the results of the experiment to find conditions that have the most optimal results so that the expected goals of the boundaries of the problems that have been set will be achieved.

Continuous investigation of the research is expected so that the control variables specified are not out of the problem boundary

\boxed{\boxed{\bold{Learn~more}}}

the scientific method steps and process

brainly.com/question/241928

the Scientific Method

brainly.com/question/5033788

scientists use the scientific method

brainly.com/question/9602076

the purpose of the scientific method

brainly.com/question/1178992

Keywords: scientific method, fixed variable, an independent variable

zlopas [31]4 years ago
3 0

An experimental investigation allows you to control the variables.

Explanation:

Experimental investigations include a method in which a "fair test" is created and variables are actively planned, managed, and measured in an attempt to gather testimony to confirm or negate a causal relationship. Experimental investigations have a control group which does not accept any treatment.

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100.00 mL of 0.15 M nitrous acid (HNO2) are titrated with a 0.15 M NaOH solution. (a) Calculate the pH for the initial solution.
wolverine [178]

Answer:

a. pH = 2.04

b. pH = 3.85

c. pH = 8.06

d. pH = 11.56

Explanation:

The nitrous acid is a weak acid (Ka = 5.6x10⁻⁴) that reacts with NaOH as follows:

HNO₂ + NaOH → NaNO₂(aq) + H₂O(l)

a. At the beginning there is just a solution of 0.12M HNO₂. As Ka is:

Ka = [H⁺] [NO₂⁻] / [HNO₂]

Where [H⁺] and [NO₂⁻] ions comes from the same equilibrium ([H⁺] = [NO₂⁻] = X):

5.6x10⁻⁴ = X² / 0.15M

8.4x10⁻⁵ = X²

X = [H⁺] = 9.165x10⁻³M

As pH = -log [H⁺]

<h3>pH = 2.04</h3><h3 />

b. At this point we have HNO₂ and NaNO₂ (The weak acid and the conjugate base), a buffer. The pH of a buffer is obtained using H-H equation:

pH = pKa + log [NaNO₂] / [HNO₂]

<em>Where pH is the pH of the buffer,</em>

<em>pKa is -log Ka = 3.25</em>

<em>And [NaNO₂] [HNO₂] could be taken as the moles of each compound.</em>

<em />

The initial moles of HNO₂ are:

0.100L * (0.15mol / L) = 0.015moles

The moles of base added are:

0.0800L * (0.15mol / L) = 0.012moles

The moles of base added = Moles of NaNO₂ produced = 0.012moles.

And the moles of HNO₂ that remains are:

0.015moles - 0.012moles = 0.003moles

Replacing in H-H equation:

pH = 3.25 + log [0.012moles] / [0.003moles]

<h3>pH = 3.85</h3><h3 />

c. At equivalence point all HNO2 reacts producing NaNO₂. The volume added of NaOH must be 100mL. That means the concentration of the NaNO₂ is:

0.15M / 2 = 0.075M

The NaNO₂ is in equilibrium with water as follows:

NaNO₂(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq) + Na⁺

The equilibrium constant, kb, is:

Kb = Kw/Ka = 1x10⁻¹⁴ / 5.6x10⁻⁴ = 1.79x10⁻¹¹ = [OH⁻] [HNO₂] / [NaNO₂]

<em>Where [OH⁻] = [HNO₂] = x</em>

<em>[NaNO₂] = 0.075M</em>

<em />

1.79x10⁻¹¹ = [X] [X] / [0.075M]

1.34x10⁻¹² = X²

X = 1.16x10⁻⁶M = [OH⁻]

pOH = -log [OH-] = 5.94

pH = 14-pOH

<h3>pH = 8.06</h3><h3 />

d. At this point, 5mL of NaOH are added in excess, the moles are:

5mL = 5x10⁻³L * (0.15mol / L) =7.5x10⁻⁴moles NaOH

In 100mL + 105mL = 205mL = 0.205L. [NaOH] = 7.5x10⁻⁴moles NaOH / 0.205L =

3.66x10⁻³M = [OH⁻]

pOH = 2.44

pH = 14 - pOH

<h3>pH = 11.56</h3>
5 0
3 years ago
Are plants and animal pH sensitive?​
Rudiy27

Answer:

Plants and animals are pH sensitive. The growth of plants is dependent on the nature of the soil. If the pH of the soil is greater than 7 and is alkaline, then the plants cannot grow in the soil.

Explanation:

6 0
3 years ago
A sample of liquid mercury is heated from 20°C to 40°C. Which measurement of the sample will increase during this process? volum
Paladinen [302]

its volume this is the answer because the mercury will turn into gas. gas has more volume because it takes up more space as it spreads.

3 0
4 years ago
Calculate the density of an object with a mass of 6.147 and a volume of 9.3 (include units)
Olin [163]
Here is the formula for density:
Density (D) = Mass (M) divided by Volume (V)

So you would do D = 6.147 divided by 9.3

As an as answer you would get: 0.6609677419g/cm^3

Additional information:

The formula for volume is:
V = M divided by D


The formula for Mass is:
M = D times V


I hope this helps :)
5 0
4 years ago
Which set of coefficients correctly balances the following chemical equation?__ AgNO3 + ___ MgCl2 --&gt; ___ AgCl + ___ Mg(NO3)2
melisa1 [442]
It is C 2 1 2 1

You have to 1st balance the nitrates then balance the silvers to get the coefficients

4 0
3 years ago
Read 2 more answers
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