Able to dissolve to a certain extent usually in reference to water

Briefly describe how a potentiometric pHmeter works. (Hint: Describe how the pH meter measures the amount of H+ or OH- ions in a

KengaRu [80]

Answer:

Indicators show changes in the pH of a solution

Explanation:

A pH meter is an instrument that measures the hydrogen-ion activity in aqueous solutions, indicating the acidity or alkalinity of the solution expressed as pH .The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, hence the pH meter is sometimes referred to as a potentiometric pH meter. Potentiometric pH meters measure the voltage between two electrodes and display the result converted into the corresponding pH value. The instrument comprises of a simple electronic amplifier and a pair of electrodes, or alternatively a combination electrode, and some form of display calibrated in pH units. It usually has a glass electrode and a reference electrode, or a combination electrode. The electrodes, or probes, are inserted into the solution to be tested.

Organic indicators are chemical species that change their colour in response to changes in the pH of the solution. This implies that the anionic and protonated forms of the indicator possess different colours. Hence the colour changes in acidic, basic and neutral solutions. The images attached indicate the colour changes in phenolphthalein and methyl orange in acidic and basic media accordingly.

4 0

3 years ago

When hydrogen is burned in the presence of oxygen it will form water, as per the equation: 2H2 + O2 -> 2H2O. Which types of r

nadya68 [22]

Answer:

B

Explanation:

Hydrogen is synthesized to water by adding Oxygen.

Hydrogen is oxidised to water by combustion ( burning in presence of oxygen).

4 0

3 years ago

Now select a longer period, say the fourth period, starting with the element in the 1A group. Again, go from left to right. What

Inessa [10]

Answer:

The pattern of change in the electron configuration increases from left to right across the period.

Explanation:

In the periodic table, elements having the same number of electrons in the outermost shell of their atoms are placed over one another in vertical columns. Each of the vertical columns is known as a group or family. while each of the resulting horizontal rows is known as a period or row.

There are 18 vertical columns and seven periods in the periodic table. Each period begins with an atom having a valence electron and ends with an atom having a complete outer shell structure of an inert gas.

The fourth period of the periodic table (d-block) consists of the transition elements.

The electron distribution into the energy levels of sublevels of atoms can be shown in any of the tree important electronic configuration.

Electronic configuration shows the sequence of filling electrons into the orbitals of the sublevels as guided by some principles.

The maximum number of electrons in the orbitals of sublevels are two for s-sublevel(one orbital) ; six for p-sublevel( three orbital); ten for d-sublevel ( five orbitals) and fourteen for f-sublevel( seven orbitals). This indicates that the maximum number of electrons in an orbital is two

In the Periodic table ,The sublevels with lower energies are filled up before those with higher energies. One important thing about this principle is that the sublevels do not fill up in numerical order. The pattern of filling is as follows:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f etc.

5 0

3 years ago

In your OWN WORDS, describe what the “Law of Conservation of Energy” is.

agasfer [191]

Energy cannot be destroyed or created, but energy could be transformed or transferred. For example a skiier skiing from the mouth can have potential energy transferred into kinetic energy.

4 0

3 years ago

Why is only one diastereomer formed in this reaction? Relate your answer to the mechanism you drew. b) If you used cis-stilbene

crimeas [40]

Answer:

1. Diastereomers have different physical properties (unlike most aspects of enantiomers) and often different chemical reactivity. ... Many conformational isomers are diastereomers as well. Diastereoselectivity is the preference for the formation of one or more than one diastereomer over the other in an organic reaction.

2. The result is a trans dibromide, as shown in the equation below

Explanation:

Diastereomers (sometimes called diastereoisomers) are a type of a stereoisomer.[1] Diasteoreomers are defined as non-mirror image non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent (related) stereocenters and are not mirror images of each other.[2] When two diastereoisomers differ from each other at only one stereocenter they are epimers. Each stereocenter gives rise to two different configurations and thus typically increases the number of stereoisomers by a factor of two.

2. the addition of bromine to the trans and

cis isomers of 1,2-diphenylethene, more commonly known as trans- and cis-stilbene.

H

H H

trans-stilbene cis-stilbene

m.p. 122-124°C b.p. 82-84°C

density 0.970 g/mL density 1.011 g/mL

M.W. 180.25 g/mol M.W. 180.25 g/mol

In both cases, the nucleophilic double bond undergoes an electrophilic addition reaction

by the bromine reagent which proceeds via a cyclic bromonium ion. The addition of

bromine begins at one side of the double bond (either side is equally likely, but only one

option is drawn) and is followed by attack of bromide ion on the bromonium ion (again,

attack could occur at either carbon since the ion is symmetric, but only one option is

drawn). The result is a trans dibromide, as shown in the equation below:

Since the cis and trans isomers of stilbene have different geometries, it follows

that upon reaction with bromine they give rise to stereoisomeric bromonium ions and,

eventually, products that differ only by their stereochemistry.

4 0

3 years ago