1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
EleoNora [17]
3 years ago
6

What are columns on the periodic table called? What is the significance of the columns on the periodic table?

Chemistry
2 answers:
Wewaii [24]3 years ago
7 0

Answer:

columns in the periodic table are reffered to as "periods". periods represent elements with the same number of shells i.e all elements in period 1 have 1 shell (k shell) and vice versa.

chubhunter [2.5K]3 years ago
3 0

Answer:

The vertical columns of the periodic table are called groups, or families. The significance is elements with similar properties are placed in the same vertical columns. The horizontal rows of the periodic table are called periods. The significance is that properties vary from left to right along the rows.

Explanation:

We just did this in science

You might be interested in
An isotope of lead can be represented by the following symbol ²⁰⁷ 82 PB. From this symbol, it can be deduced that one atom of th
9966 [12]

Answer:

B) 82 protons

Explanation:

The number of protons for an element never change. 82 Is the atomic number for Pb which is how many protons it has. An isotope means it has more neutrons.

6 0
3 years ago
Copper(II) sulfate pentahydrate, CuSO4 ·5 H2O, (molar mass 250 g/mol) can be dehydrated by repeated heating in a crucible. Which
prohojiy [21]

Answer:

The water lost is 36% of the total mass of the hydrate

Explanation:

<u>Step 1:</u> Data given

Molar mass of CuSO4*5H2O = 250 g/mol

Molar mass of CuSO4 = 160 g/mol

<u>Step 2:</u> Calculate mass of water lost

Mass of water lost = 250 - 160 = 90 grams

<u>Step 3:</u> Calculate % water

% water = (mass water / total mass of hydrate)*100 %

% water = (90 grams / 250 grams )*100% = 36 %

We can control this by the following equation

The hydrate has 5 moles of H2O

5*18. = 90 grams

(90/250)*100% = 36%

(160/250)*100% = 64 %

The water lost is 36% of the total mass of the hydrate

8 0
3 years ago
Which of the following is a true statement?
sergejj [24]

Answer:

C

Explanation:

Wind is geological therefore it is geological weathering

5 0
3 years ago
Moles/Mass/Molecules Practice Problem Worksheet
Komok [63]

Answer:

Explanation:

1) Convert 11.03 moles of calcium nitrate to grams.

Given data:

Number of moles = 11.03 mol

Mass of calcium nitrate = ?

Solution:

Formula:

Number of moles = mass / molar mass

Now we will rearrange the formula because we have to calculate the mass.

Mass = number of moles × molar mass

Molar mass of calcium nitrate =  164.088 g/mol

Mass = 11.03 mol ×  164.088 g/mol

Mass = 1809.89 g

2. How many molecules are contained in 103.4g of sulfuric acid?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules = ?

Mass of sulfuric acid = 103.4 g

Solution:

Formula:

Number of moles = mass / molar mass

Number of moles = 103.4 g/ 98.079 g/mol

Number of moles = 1.05 mol

1 mole =  6.022 × 10²³ molecules

1.05 mol × 6.022 × 10²³ molecules / 1mol

6.323 × 10²³ molecules of sulfuric acid

3. 3.25 x 1024 molecules of dinitrogen pentoxide would be how many moles?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules of dinitrogen pentoxide = 3.25 × 10²⁴

Moles of dinitrogen pentoxide = ?

Solution:

1 mole =  6.022 × 10²³ molecules

1 mol  × 3.25 × 10²⁴ molecules / 6.022 × 10²³ molecules

5.4 moles

4. What would be the mass of 9.03 x 1021 molecules of hydrobromic acid?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules of hydrobromic acid = 9.03 × 10²¹

Mass of hydrobromic acid = ?

Solution:

First of all we will calculate the moles of hydrobromic acid.

1 mole =  6.022 × 10²³ molecules

1 mol  × 9.03 × 10²¹ molecules / 6.022 × 10²³ molecules

0.015  moles

Mass of hydrobromic acid:

Mass =  number of moles × molar mass

Mass = 0.015 mol × 80.9 g/mol

Mass =1.21 g

5. A sample of iron (III) chloride has a mass of 26.29g. How many moles would this be?

Given data:

Number of moles =?

Mass of iron(III) chloride = 26.29 g

Solution:

Formula:

Number of moles = mass / molar mass

Molar mass of iron chloride  =  162.2 g/mol

Now we will put the values in formula.

Moles = 26.29 g/ 162.2 g/mol

Moles = 0.16 g

6 0
3 years ago
At what temperature is the following reaction feasible: HCl(g) + NH3(g) -&gt; NH4Cl(s)?
Nutka1998 [239]
Energy is distributed not just in translational KE, but also in rotation, vibration and also distributed in electronic energy levels (if input great enough, bond breaks).

All four forms of energy are quantised and the quanta ‘gap’ differences increases from trans. KE ==> electronic.

Entropy (S) and energy distribution: The energy is distributed amongst the energy levels in the particles to maximise their entropy.

Entropy is a measure of both the way the particles are arranged AND the ways the quanta of energy can be arranged.

We can apply ΔSθsys/surr/tot ideas to chemical changes to test feasibility of a reaction:

ΔSθtot = ΔSθsys +  ΔSθsurr

ΔSθtot must be >=0 for a chemical change to be feasible.

For example: CaCO3(s) ==> CaO(s) + CO2(g) 

ΔSθsys = ΣSθproducts – ΣSθreactants 

ΔSθsys = SθCaO(s) + SθCO2(g) – SθCaCO3(s) 

ΔSθsurr is –ΔHθ/T(K) and ΔH is very endothermic (very +ve),

Now ΔSθsys is approximately constant with temperature and at room temperature the ΔSθsurr term is too negative for ΔSθtot to be plus overall.

But, as the temperature is raised, the ΔSθsurr term becomes less negative and eventually at about 800oCΔSθtot becomes plus overall (and ΔGθ becomes negative), so the decomposition is now chemically, and 'commercially' feasible in a lime kiln.

CaCO3(s) ==> CaO(s) + CO2(g)  ΔHθ = +179 kJ mol–1  (very endothermic)

This important industrial reaction for converting limestone (calcium carbonate) to lime (calcium oxide) has to be performed at high temperatures in a specially designed limekiln – which these days, basically consists of a huge rotating angled ceramic lined steel tube in which a mixture of limestone plus coal/coke/oil/gas? is fed in at one end and lime collected at the lower end. The mixture is ignited and excess air blasted through to burn the coal/coke and maintain a high operating temperature.
ΔSθsys = ΣSθproducts – ΣSθreactants
ΔSθsys = SθCaO(s) + SθCO2(g) – SθCaCO3(s) = (40.0) + (214.0) – (92.9) = +161.0 J mol–1 K–1
ΔSθsurr is –ΔHθ/T = –(179000/T)
ΔSθtot = ΔSθsys +  ΔSθsurr
ΔSθtot = (+161) + (–179000/T) = 161 – 179000/T
If we then substitute various values of T (in Kelvin) you can calculate when the reaction becomes feasible.
For T = 298K (room temperature)

ΔSθtot = 161 – 179000/298 = –439.7 J mol–1 K–1, no good, negative entropy change

For T = 500K (fairly high temperature for an industrial process)

ΔSθtot = 161 – 179000/500 = –197.0, still no good

For T = 1200K (limekiln temperature)

ΔSθtot = 161 – 179000/1200 = +11.8 J mol–1 K–1, definitely feasible, overall positive entropy change

Now assuming ΔSθsys is approximately constant with temperature change and at room temperature the ΔSθsurr term is too negative for ΔSθtot to be plus overall. But, as the temperature is raised, the ΔSθsurr term becomes less negative and eventually at about 800–900oC ΔSθtot becomes plus overall, so the decomposition is now chemically, and 'commercially' feasible in a lime kiln.
You can approach the problem in another more efficient way by solving the total entropy expression for T at the point when the total entropy change is zero. At this point calcium carbonate, calcium oxide and carbon dioxide are at equilibrium.
ΔSθtot–equilib = 0 = 161 – 179000/T, 179000/T = 161, T = 179000/161 = 1112 K

This means that 1112 K is the minimum temperature to get an economic yield. Well at first sight anyway. In fact because the carbon dioxide is swept away in the flue gases so an equilibrium is never truly attained so limestone continues to decompose even at lower temperatures.

8 0
3 years ago
Read 2 more answers
Other questions:
  • A mass of the crucible (g) 88.000g
    9·1 answer
  • What property do all of the group 18 elements have that make them stand out from other elements?
    10·1 answer
  • What is the overall charge of an ion that has 12 protons, 10 electrons, and 14 neutrons?
    14·1 answer
  • According to its periodic table entry, how many electrons does nitrogen have in its valence level?
    13·1 answer
  • An amino acid A, isolated from the acid-catalyzed hydrolysis of a peptide antibiotic, gave a positive ninhydrin test and had a s
    8·1 answer
  • What occurs in dissociation
    15·2 answers
  • How many moles are in 4.6 x 10^19 atoms? <br><br> *#27 is the question
    10·1 answer
  • Which is produced in a synthesis reaction? O a single element O a single compound O a single ion O a single atom​
    7·2 answers
  • Please help
    14·1 answer
  • A student delivered 17.06 mL (V1) of 7.16 % stock solution (M1) using a graduated pipette into a 50.00 mL (V2) volumetric flask.
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!