Answer:
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Explanation:
Answer:
- <u><em>It is positive when the bonds of the product store more energy than those of the reactants.</em></u>
Explanation:
The <em>standard enthalpy of formation</em>, <em>ΔHf</em>, is defined as the energy required to form 1 mole of a substance from its contituent elements under standard conditions of pressure and temperature.
Then, per defintion, when the elements are already at their standard states, there is not energy involved to form them from that very state; this is, the standard enthalpy of formation of the elements in their standard states is zero.
It is not zero for the compounds in its standard state, because energy should be released or absorbed to form the compounds from their consituent elements. Thus, the first choice is false.
When the bonds of the products store more energy than the those of the reactants, the difference is:
- ΔHf = ΔHf products - ΔHf reactants > 0, meaning that ΔHf is positive. Hence, the second statement is true.
Third is false because forming the compounds may require to use (absorb) or release (produce) energy, which means that ΔHf could be positive or negative.
Fourth statement is false, because the standard state of many elements is not liquid. For example, it is required to supply energy to iron to make it liquid. Thus, the enthalpy of formation of iron in liquid state is not zero.
I believe the answer is D. loess. The loess soil is a predominantly silt-sized sediment formed by accumulation of wind blown dust. This soil is highly porous, homogeneous, pale yellow and friable. One way of forming loess is from glaciers and that is why they contain glacially ground flour like clay and silt.
Answer:
WCl₂, WCl₄, WCl₅, WCl₆
Explanation:
Molar Mass of Tungsten = 184 g/mol
Mass of Chlorine = 35.5 g/mol
In the first compound;
Percentage of tungsten = 72.17 %
Upon solving;
72.17 % = 184
100 % = Total mass
Total mass of compound = 254.95g
Mass of chlorine = 254.95 - 184 = 70.95 (Dividing by 35.35; This is approximately 2 Chlorine atoms.
The Formular is WCl₂
In the second compound;
Percentage of tungsten = 56.45 %
Upon solving;
56.45 % = 184
100 % = Total mass
Total mass of compound = 325.95 g
Mass of chlorine = 325.95 - 184 = 141.95g (Dividing by 35.35; This is approximately 4 Chlorine atoms.
The Formular is WCl₄
In the third compound;
Percentage of tungsten = 50.91 %
Upon solving;
50.91 % = 184
100 % = Total mass
Total mass of compound = 361.42 g
Mass of chlorine = 361.42 - 184 = 177.42 (Dividing by 35.35; This is approximately 5 Chlorine atoms.
The Formular is WCl₅
In the fourth compound;
Percentage of tungsten = 46.39 %
Upon solving;
46.39 % = 184
100 % = Total mass
Total mass of compound = 396.64 g
Mass of chlorine = 396.64 - 184 = 212.64 (Dividing by 35.35; This is approximately 6 Chlorine atoms.
The Formular is WCl₆
In a crystal, the particles are arranged in an orderly, repeating, three-dimensional pattern.
Option C
<u>Explanation:</u>
Solid crystal particles can be ions, molecules or atoms, based on the material kind. The three-dimensional solid crystal system is called the crystal lattice. The crystals are divided into general categories according to their shape.
The crystal is characterized by faces that intersect at specific angles characteristic of this material. Crystal is a material in which particles get arranged in an ordered, repeatable, three-dimensional way. Means, a solid contains an atomic patterns that is uniformly repeated in three dimensions.
