Use the information provided to (a) fill in the table below and (b) show your calculations for 1 trial below the table. The experiment conducted in this part is a titration using KHP as the primary standard to titrate a solution of NaOH of unknown concentration. The experimental procedure is as described on pages 46- 47 of the lab manual. To correctly perform the calculations asked for below, focus on the following:
1. Identify exactly what acid and base reagents are used. Determine molar mass of KHP for gram to mole conversion.
2. Use a balanced reaction for the titration to determine the mole to mole ratio of acid to base (see lab manual).
3. Use this mole to mole ratio as well as the mathematical relationships between moles, volume and molarity to determine the molarity of NaOH for each trial below.
4. For all molarity calculations, you will need to work in liters, as M = mol/L
5. 6 samples of KHP were titrated with NaOH of unknown concentration to the equivalence point. Perform the necessary calculations and fill in the table found below.
Experimental Data
Trial # Mass of Moles of Volume of Molarity of
KHP KHP NaOH dispensed NaOH,
titrated titrated at the end point calculated (mol/L)
1 0.480 g 21.89 mL
2 0.485 g 21.89 mL
3 0.491 g 22.28 mL
4 0.497 g 22.77 mL
5 0.503 g 22.79 mL
6 0.513 g 23.48 mL
Average
Molarity:
Show calculations for trial 1 only used for the following:
Moles of KHP in trial 1:
Molarity of Sodium Hydroxide solution in trial 1:
1. What is Potassium Hydrogen Phthalate and why is it used for standardization of an NaOH solution?
2. In a similar experiment to Part I, a solution of calcium hydroxide of unknown concentration is standardized against potassium hydrogen phthalate (KHP). From the data below, calculate the molarity of Ca(OH)2 solution. The balanced reaction is:
Ca(OH)2 + 2KHC8H4O4 à CaC8H4O4 + K2C8H4O4 + 2H2O
Note the 1:2 mole to mole ratio of calcium hydroxide to KHP.
Mass of KHP consumed at titration end point: 0.914 g
Ca(OH)2 titrated to reach endpoint: 26.42 ml
3. Determine how many liters of the standardized Ca(OH)2 in question 2 will be needed to neutralize an aqueous solution containing 0.1453 g of oxalic acid dihydrate (126.07 g/mol). The balanced reaction is:
H2C2O4 + Ca(OH)2 → CaC2O4 + 2 H2O

the correct answer is boyle

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

pre-sliced bread is a relatively recent development in baking technology. previous to that, it was always sold in a bakery in daily-made contiguous loaves with no wrapping, and was moderately perishable, usually being used with a day or two (which is why every bakery had a discounted “day-old” bread table.) therefore, pre-sliced bread would grow stale quickly. the hard crust provided a protective layer, and once the exposed dry slice left from the previous cut was removed, the interior was still soft.

what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.