The pH of the solution is 3,76
Why?
To solve this problem we have to apply the Henderson-Hasselbach equation, which is used whenever we need to calculate the pH of a solution of an acid HA (Lactic Acid) and its conjugate base A⁻ (Sodium Lactate)
We can use either moles or concentrations for this equation. In this case, we are going to use the moles, and we are going to take the pKa of lactic acid as 3,86:
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Answer:
Explanation:
We are asked to convert an amount in grams to moles. To do this, we use the molar mass. This is the number of grams in one mole of a substance. It is the same value numerically as the atomic mass on the Periodic Table, however the units are grams per mole, not atomic mass units.
Look up the molar masses for the individual elements.
Look back at the formula: Na₂O. Notice there is a subscript of 2 after sodium. This means there are 2 atoms of sodium in every molecule, so we have to multiply sodium's molar mass by 2 before adding oxygen's.
Set up a ratio using the molar mass.
Multiply by the given number of grams.
Flip the ratio so the grams of sodium oxide can cancel each other out.
The original measurement of grams given has 3 significant figures, so our answer must have the same. For the number we calculated, that is the hundredth place.
The 4 in the thousandth place tells us to leave the 8.
There are <u>2.48 moles of sodium oxide</u> in 154 grams, so choice A is correct.
Steam is the gaseous phase of water. It is used in some cases to melt ice. Melting of ice is the conversion of solid water to liquid water. This is just a phase change in which water changes its state from solid state to liquid state. But the chemical composition of water remains unchanged. Water has the same molecular formula in both the solid (ice) and liquid states. Hence, the conversion of solid ice to liquid water by steam refers to a physical change.