Answer:
The correct answer is They provide the molar ratio of reactant and products in a chemical reaction.
Explanation:
Balanced chemical equation helps us to calculate the number of moles of both reactant and product.For example
2H2+O2=2H2O
From the above balanced equation it can be stated that 2 molecules of hydrogen(H2) reacts with 1 molecule of oxygen(O2) to form 2 molecules of water.
<span>0.0200 L X 0.06 mol/L HCl = 1.2X10^-3 mol HCl
Moles NaOH added to reach equivalence point = 1.2X10^-3 mol NaOH
Volume NaOH = 1.2X10^-3 mol / 0.0400 M NaOH = 0.030 L NaOH = 30 mL NaOH
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D.There is a rapid change in pH near the equivalence point (pH = 7)
hope it helps
The answer to this question is <span>b) hydrogen chloride (HCl) is added to the system. This is the only acid/base on the list. Only acids and bases have the potential to directly change pH as they contribute hydronium and hydroxide ions. Glucose, sodium chloride, and sodium bromide do not affect pH in the first place.</span>
Answer:
The number of atoms is the same in the reactants and in the products, and the total mass is the same in the reactants and in
the products
Explanation:
For an equation to termed balance, the number of atoms of elements in the reactants must be equal to the number of atoms of the same element in the product.
The law of conservation of mass states that matter can neither be created nor destroyed during a chemical reaction but changes from one form to another. An unbalanced equation simply means that matter have been created or destroyed. This implies that balancing equation supports the laws of conservation of mass
Answer:
- <u><em>It is positive when the bonds of the product store more energy than those of the reactants.</em></u> (the second statement)
Explanation:
ΔHf is the change of enthalpy during the reaction, which is equal to the sum of enthaply changes of the products less the sum of the enthalpy changes of the reactants.
- ΔHf = ∑ (ΔH products) - ∑ (ΔH reactants)
Also, ΔHrxn, per definition, is the potential chemical energy stored in the bonds of the products less the chemical potential energy stored in the bonds of the reactants.
Then, when the potential chemical energy stored in the bonds of the products is greater than the chemical potential energy stored in the bonds of the reactants ΔHrxn is positive.
Hence, you conclude that ΔHf is positive when the bonds of the product store more energy than those of the reactants (second statement from the choices).
Some brief comments about the other statements:
- The standard enthalpy of formation, ΔHf, is zero for an element in its standard state, not for a compound.
- For a compound the enthalpy of formation at 25ºC and 1 atm (the standard state) may be positive or negative.
- Also, note that the standard state for any element is not liquid: some are solids, some are gases, and some are liquids at 25ºC and 1 atm.
