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labwork [276]
2 years ago
14

A Variable That Stays The Same In An Experiment Is A ?

Chemistry
1 answer:
hammer [34]2 years ago
3 0
The variable that stays the same in an experiment is called the controlled variable

Hope this helps
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Electrons are found in energy levels around the nucleus of an atom. Energy levels can also be called ""shells."" The energy leve
melamori03 [73]

Answer:

<u>The first electronic shell or energy level, having n= 1, called the K shell, is the closest to the nucleus.</u>

Explanation:

In an atom, the sub atomic particles called electrons, revolve around the nucleus of the given atom at different <em>energy levels</em>, called <em>shells</em>.

The energy levels or the electronic shells are denoted by the <em>principal quantum number</em>  <em>(n)</em> and has the following values n = 1, 2, 3, 4, 5, 6, 7; <em>from the innermost shell to the outermost.</em>

The electron shells are also labelled by the alphabets, K, L, M, N, O, P, and Q, <em>from the innermost shell to the outermost.</em>

<u><em>Thus the first electronic shell having n= 1, called K shell, is the lowest energy level and is present closest to the nucleus.</em></u>

<u><em>Whereas, the last electronic shell having n =7, called Q shell, is the highest energy level and is farthest from the nucleus.</em></u><u> </u>

5 0
3 years ago
You are instructed to create 900. mL of a 0.29 M phosphate buffer with a pH of 7.8. You have phosphoric acid and the sodium salt
Aleksandr [31]

Answer:

B and C

Explanation:

When we have to do a buffer solution we always have to choose the reaction that has the <u>pKa closer to the desired pH value</u>. When we find the pKa values we will obtain:

pKa_1=-Log[6.9x10^-^3]=2.16

pKa_2=-Log[6.2x10^-^8]=7.20

pKa_3=-Log[4.8x10^-^13]=12.31

The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which  H_2PO_4^-^1 is the <u>acid</u> and HPO_4^-^2 is the <u>base</u>. Therefore the answer for the first question is B and the answer for the second question is C.

8 0
2 years ago
Based on your knowledge of factors that affect the rates of chemical reactions, predict the trend in the last column of the expe
Anika [276]

Factors that increases reaction rate such as increase in concentration or pressure will reduce reaction time whereas factors that decrease reaction rate such as inhibitors will increase reaction time.

<h3>What are the factors that affect reaction rate?</h3>

Factors that affect reaction rate are those factors which increase or decrease the rate of chemical reaction.

The factors that affect reaction rate include:

  • temperature
  • concentration/pressure
  • catalysts
  • surface area
  • nature of substance

Any factor that increases reaction rate such as increase in concentration or pressure will reduce reaction time whereas factors that decrease reaction rate such as inhibitors will increase reaction time.

Learn more about factors affecting reaction rate at: brainly.com/question/14817541

#SPJ1

6 0
2 years ago
Assuming equal concentrations and complete dissociation, rank these aqueous solutions by their freezing points. nh4cl cobr3 k2so
Illusion [34]
Answer: CoBr3 < K2SO4 < NH4 Cl

Justification:

1) The depression of the freezing point of a solution is a colligative property, which means that it depends on the number of particles of solute dissolved.

2) The formula for the depression of freezing point is:

ΔTf = i * Kf * m

Where i is the van't Hoof factor which accounts for the dissociation of the solute.

Kf is the freezing molal constant and only depends on the solvent

m is the molality (molal concentration).

3) Since, you are assuming equal concentrations and complete dissociation of the given solutes, the solute with more ions in the molecular formula will result  in the solution with higher depression of the freezing point (lower freezing point).

4) These are the dissociations of the given solutes:

a) NH4 Cl (s) --> NH4(+)(aq) + Cl(-) (aq) => 1 mol --> 2 moles

b) Co Br3 (s) --> Co(3+) (aq) + 3Br(-)(aq) => 1 mol --> 4 moles

c) K2SO4 (s) --> 2K(+) (aq) + SO4 (2-) (aq) => 1 mol --> 3 moles

5) So, the rank of solutions by their freezing points is:

CoBr3 < K2SO4 < NH4 Cl
4 0
3 years ago
Read 2 more answers
What is the molar mass of a substance
aleksandrvk [35]
<span>47.88 g/mol is the awsner your welcome</span>
3 0
3 years ago
Read 2 more answers
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