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Verdich [7]
3 years ago
9

There are ____ main groups in the modern periodic table of elements

Chemistry
1 answer:
antoniya [11.8K]3 years ago
5 0

There are 18 numbered groups in the periodic table, and the f-block columns (between groups 3 and 4) are not numbered. The elements in a group have similar physical or chemical characteristics of the outermost electron shells of their atoms (i.e., the same core charge), as most chemical properties are dominated by the orbital location of the outermost electron. There are three systems of group numbering. The modern numbering group 1 to group 18 is recommended by the International Union of Pure and Applied Chemistry (IUPAC). It replaces two older naming schemes that were mutually confusing. Also, groups may be identified by their topmost element or have a specific name. For example, group 16 is variously described as the oxygen group and as the chalcogens.

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60 kg of fuel was completely burnt for an experiment. The amount of heat energy was found to be 180000KJ. Calculate calorific va
FrozenT [24]

Answer:

3000 kJ/kg

Explanation:

The calorific value of a substance is the amount of heat produced per unit mass by the combustion of the substance.

It is given by:

C=\frac{Q}{m}

where

Q is the amount of heat released

m is the mass of the fuel

In this problem, we have:

m = 60 kg is the mass of fuel

Q=180,000 kJ is the amount of heat released

Therefore, the calorific value of the fuel is:

C=\frac{180,000}{60}=3000 kJ/kg

6 0
2 years ago
For the vaporization reaction Br2(l) → Br2(
oksian1 [2.3K]
    The  temperature  at   which  the  process  be   spontaneous  is  calculated  as  follows

delta  G  =  delta H  -T delta S

let  delta G  be =0

therefore  delta H- T  delta s =0

therefore  T=  delta  H/  delta  S
convert  31   Kj  to  J  =  31  x1000=  31000 j/mol

T=31000j/mol /93 j/mol.k =333.33K


3 0
3 years ago
Mayonnaise is made up of eggs, oil, and vinegar. Under which category it should be classified? elements compounds solutions coll
krok68 [10]
Mayonnaise is a heterogeneous mix. The correct answer is colloids.
8 0
2 years ago
Read 2 more answers
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Doss [256]

1: it is +2

2: it is +6

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8 0
2 years ago
According to reference table adv-10, which reaction will take place spontaneously?
olga_2 [115]
Missing table!! write the elements with the first letter of the symbol with Upper Caps letters!!!

http://www.chemeddl.org/services/moodle/media/QBank/GenChem/Tables/EStandardTable.htm

<span>Ni2+ +Pb(s) → Ni(s) + Pb2+
</span>The potential of the oxidation of Pb(s) --> Pb2+(aq) is 0.126 V 
The potential of the reduction go Ni2+(aq) --> Ni(s) is -0.25 V 

<span>Add the two together and the potential for the reaction is -0.124 V (NO SPONTANEOUS THE SIGN IS NEGATIVE)

</span><span>au3+ + al(s) → au(s) + al3+Au3+(aq) ->   Au(s)  +1.5 VAl -> Al3+  +1.66VV= 3.16 (SPONTANEOUS THE SIGN OF THE PONTENTIAL IS POSITIVE)</span><span>Sr2+ + Sn(s) → Sr(s) + Sn2+
</span>
Sr2+(aq) + 2 e–  <span>  Sr(s)  V= -2.89V
</span>Sn -> Sn2+ V= 0.14 V
V= -2.75 V (no spontaneous)

<span>Fe2+ + Cu(s) → Fe(s) + Cu2+
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V= - 0.777V (no spontaneous)
5 0
2 years ago
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