Can you help me answer the question ?

Why do lithium (Li) and sodium (Na) have similar properties?

ella [17]

B, they belong to group 1

A: Li is period 2 and Na is period 3

C: Na has one more electron shell

D: Not related to how it is spelled

8 0

3 years ago

What evidence supports Bohr’s claim that an electron is found only in specific energy levels around the nucleus of the atom. And

Lorico [155]

Energy Levels of Electrons. As you may remember from chemistry, an atom consists of electrons orbiting around a nucleus. ... They are restricted to orbits with only certain energies. Electrons can jump from one energy level to another, but they can never have orbits with energies other than the allowed energy levels.

4 0

3 years ago

Read 2 more answers

At 63.5 C the vapor pressure of H2O is 175 torr and that of ethanol is 400 torr. A solution is made by adding equal masses of H2

xxTIMURxx [149]

Answer:

Moel fraction of ethanol in the solution = 0.28

Vapor pressure of the solution = 238 torr

Mole fraction of ethanol in the vapor = 0.47

Explanation:

Let's use 100 g of each substance as a calculus basis. Knowing that the molar mass of water is 18 g/mol and the molar mass of ethanol is 46 g/mol, the number of moles (n = mass/molar mass) of each one is:

nw = 100/18 = 5.56 mol

ne= 100/46 = 2.17 mol

The total number of moles is 7.73 mol, so the mole fraction of ethanol is

2.17/7.73 = 0.28

The mole fraction of water must be 0.72, so if we assume that the solution is ideal, by the Raoult's law, the solution vapor pressure is the sum of the multiplication of the mole fraction by the vapor pressure of each substance, thus:

P = 0.28*400 + 0.72*175

P = 238 torr

The partial pressure of each substance can be found by the multiplication of the molar fraction by the vapor pressure, thus:

Pw = 0.72*175 = 126 torr

Pe = 0.28*400 = 112 torr

To know the number of moles that is vaporized above the solution, we may use the ideal gas law:

PV = nRT

P/n = RT/V

R is the gas constant, T is the temperature and V is the volume, so they are the same for both water and ethanol, thus

Pw/nw = Pe/ne

126/nw = 112/ne

ne = (112/126)*nw

ne = 0.89nw

So, the mole fraction of ethanol is:

ne/(ne + nw) = 0.89nw/(0.89nw + nw) = 0.89/1.89 = 0.47

4 0

3 years ago

Explain how scientists learned about the magnetic poles of the Earth.

Oxana [17]

Answer:

ocean basalts

Explanation:

As the sea floor slowly spreads, the igneous rock(ocean basalts) of which it is comprised cools and congeals, recording the earth's current magnetic pole alignment.

5 0

3 years ago

I don’t need the answers to this but u can if u want but I’m just asking what is this is asking for and how to solve it? I hope

strojnjashka [21]

Answer:

See explanation

Explanation:

Salts are produced from the reaction of an acid and a base. In general ...

Acid + Base => Salt + Weak Electrolyte

Acids from the 'Arrhenius Definition' contain an 'ionizable' hydrogen (-H). Such as, HCl, HBr, HI, HNO₃, HClO₄, HF, etc.

Bases from the 'Arrhenius Definition' contain an 'ionizable' hydroxide (-OH). Such as, LiOH, NaOH, KOH, CsOH, Ca(OH)₂, etc.

When the acid and base react, they proceed by what is known as a 'Double Replacement Reaction' or 'Metathesis Reaction'. In the process, the ions of the reactant compounds exchange positions such that a 'Driving Force' compound is formed on the product side. The Driving Force compound is <u>always</u> on the product side of the equation and is a compound that takes one of three forms => A precipitating salt, a compound of a weak acid or weak base (weaker than the starting acid or base) or gas decomposition product (~ vinegar + backing soda rxn => CO₂ gas).

For your problem, split the compound into cations and anions. You can usually tell which is which by using this format on formulas like those listed in your question => reading formula from left to right, place an imaginary line after the 1st metal => this metal will be the cation & the remaining formula will be the anion.

KBr => K | Br => K (Potassium) is the cation (K⁺) and Br (Bromide) is the anion (Br⁻)

KBr => K⁺ + Br⁻

Now. Apply this rule => Add 'H' to anion => HBr, then add 'OH' to cation => KOH.

HBr is the acid and KOH is the base. Therefore ...

Acid + Base => Salt + Wk Electrolyte

HBr + KOH => KBr + H₂O (note how ions of reactants exchange places to form products).

So, KBr comes from the reaction of acid HBr and base KOH.

HBr + KOH => KBr + H₂O

To determine the acid and base origins of LiCl and NaF, use the same logic. Hope this helps. Doc :-)

7 0

3 years ago