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.
Answer:
The seven crystal systems are a method of classifying crystals according to their atomic lattice or structure. The atomic lattice is a three dimensional network of atoms that are arranged in a symmetrical pattern. The shape of the lattice determines not only which crystal system the stone belongs to, but all of its physical properties and appearance. In some crystal healing practices the axial symmetry of a crystal is believed to directly influence its metaphysical properties. For example crystals in the Cubic System are believed to be grounding, because the cube is a symbol of the element Earth.
Explanation:
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<h3>Answer:</h3>
Ionic Bond
<h3>Explanation:</h3>
Types of Bonds can be predicted by calculating the difference in electronegativity.
If, Electronegativity difference is,
Less than 0.4 then it is Non Polar Covalent Bonding
Between 0.4 and 1.7 then it is Polar Covalent Bonding
Greater than 1.7 then it is Ionic Bonding
For Mg and Cl,
E.N of Chlorine = 3.16
E.N of Magnesium = 1.31
________
E.N Difference 1.85 (Ionic Bond)
<h3>Conclusion:</h3>
MgCl₂ being ionic in nature when dissolved in water dissociates into Magnesium and Chloride ions respectively.
Answer:
Hello I didi this quiz and i got 100% and the answer is (a) hope this helps <3
Explanation:
A scientific law describes an observed occurrence or phenomena.
