All energy waves other than the visible light spectrum cannot be seen. true or false

How does atomic radius change within groups and across periods in the periodic table

Aleks [24]

<span>In general,atomic size increases from top to bottom within a group and decreases from left to right across a period</span>

4 0

4 years ago

A polymer sample combines five different molecular-weight fractions, each of equal weight. The molecular weights of these fracti

kakasveta [241]

Answer:

Mn = 43,783

Mw = 60,000

Mz = 73,333

narrow distribution = 1.37

Explanation:

The molecular weights of these fractions increase from 20,000 to 100,000 in increments of 20,000. This means their Mi is respectively: (The molar weight (Mi) of the fractions)

Fraction 1 : Mi = 20 *10^3

Fraction 2: Mi = 40 *10^3

Fraction 3 : Mi = 60 *10^3

Fraction 4: Mi = 80 *10^3

Fraction 5 : Mi = 100 *10^3

The ΣMi = 300*10^-3

The Wi (mass of the fractions is for all the fractions the same, let's say 1)

So Wi = 1+1+1+1+1 = 5

Since number of moles = mass / Molar mass

The number of moles is respectively: ni = Wi/Mi (x10^5)

Fraction 1 : ni = Wi/Mi = 1/20000 = 5

Fraction 2: ni = 1/40000 = 2.5

Fraction 3 : ni =1/60000 = 1.67

Fraction 4: ni = 1/80000 = 1.25

Fraction 5 : ni= 1/100000 = 1

The Σni = 11.42

Mn = ΣWi/ni = 5/11.42*10^-5 = 43,783

Mw = (ΣWi * Mi)/ΣWi = 300,000 /5 = 60,000

Mz = (ΣWi * Mi²)/ΣWi *Mi = (4*10^8 +16*10^8 +36*10^8 +64*10^8 +100*10^8) /300,000 =73,333

Mz/Mn = narrow distribution =60,000/43,783 = 1.37

7 0

3 years ago

Read 2 more answers

In the reaction between bromine and sodium, a bromine atom gains an electron. What ion is formed? Is the bromine oxidized, or is

SVETLANKA909090 [29]

Answer: The ion formed after the reduction of bromine is $Br^-$

Explanation:

The electronic configuration of Sodium (Na) = $[Ne]3s^1$

The electronic configuration of Bromine (Br) = $[Ar]3d^{10}4s^24p^5$

From the above configurations, Sodium ion will loose 1 electron in order to gain stable electronic configuration and that electron is accepted by the Bromine atom because it is 1 electron short of the stable electronic configuration.

$Na\rightarrow Na^++e^-$ (oxidation reaction)

$Br+e^-\rightarrow Br^-$ (Reduction reaction)

Bromine atom is reduced to form $Br^-$

Reduction reactions are the reactions in which the element gain electrons.

Oxidation reactions are the reactions in which the element looses its electrons.

3 0

4 years ago

Read 2 more answers

If you remove two protons and two neutrons from a gold atom (au), what new element is formed (if any)?

ivanzaharov [21]

Answer: Iridium

Explanation:

The atomic number of Iridium is 77.

8 0

2 years ago

A flashlight battery is an example of a

kompoz [17]

<span>Dry cell battery

When an automotive battery is fully charged, the sulfuric acid and water mixture will have a specific gravity of about 1.3. Specific gravity is actually the difference in the weight of water in comparison to a specific fluid. It is measured by a hydrometer. The amount of charge in the battery is normally measured by the specific gravity of the battery. The specific gravity of water is 1 and anything less than one is considered less dense while anything that has a specific gravity of more than 1 is considered more dense than water. </span>

7 0

3 years ago