Chemistry Answers

Two analy‎sts deter‎mined compos‎ition of a 2.500-g s‎oda ash sa‎mple. They divid‎ed s‎ample into two equa‎l 1.250-g par‎ts and analyz‎ed it separa‎tely through do‎uble indi‎cator titrat‎ion.

One of them dissolved sample in water to prepare a 250.0 mL stock solution. A 50.00 mL aliquot was titrated using 0.10 M HCl. A volume of 40.08 mL was measured using phenolphthalein indicator and 13.58 mL with the methyl orange indicator.

Another al‎so also dissolved sample in water to prepare a 250.0 mL stock solution. However, they spilled the primary standard, 100% pure Na2CO3, in the solution. They titrated a 50.00 mL aliquot using 0.10 M HCl same way first one did. For methyl orange indicator, they measured a volume of 30.07 mL

MW: NaOH (40.00 g/mol), Na2CO3 (105.99), NaHCO3 (84.01)

a. What is/are component/s of original soda ash sample?

b. What is/are %composition (in %w/w) of original soda ash sample?

c. How much Na2CO3 (in grams) did second spill in solution?

Hint: You do not need vph to solve this

How many moles are in 987.0 grams of Ra(OH)2

a. A solution of HCl is known to be 0.5622 N. When titrated against KOH, 45.22 ml of the acid neutralized 48.23 ml of the base. Calculate the N of the base.1.    A solution of HCl is known to be 0.5622 N. When titrated against KOH, 45.22 ml of the acid neutralized 48.23 ml of the base. Calculate the N of the base.

b. What is the N of the solution of KOH if 45.18 ml are required to neutralize 0.3000 g of pure oxalic acid dehydrate (H₂C₂O₄°2H₂O)?

Hint: N x ml = g/MW/no. of H⁺ or OH^- or +cation x 1000 

where N x ml = no. of milliequivalent weight and g/MW/no. of H⁺ or OH^- or +cation x 1000 = no. of milliequivalent weight

A 0.00453 L of sodium chloride solution was needed in a 560 mg sample that assayed

87.1% (w/w) Na2SO4. Calculate the molar concentration of sodium chloride in the

solution.

1. Coal gasification converts coal into a combustible mixture of carbon monoxide and hydrogen, called coal gas, in a gasifier: H2Oq) + C(s) –→ CO(g)+ H2(g) AHo = ? Calculate the standard enthalpy change for this reaction from the following chemical equations: 2 C(s) + O2(g)→ 2 CO(g) AHo = -222 kJ 2 H2(g) + O2(g) → H2O1) → 2H2O(g) AHo = -484 kJ H2O(g) AHo = +44 kJ This coal gas can be used a fuel: CO(g) + H2(g) + O2(g) CO2(g) + H2O(g) 2. Predict the change in enthalpy for this combustion reaction from the following equations: 2 C(s) + O2(g) → 2 CO(g) AHo = -222 kJ C(s) + O2(g) 2 Н(9) + Ог(g) → CO2(g) AHo = -394 kJ 2H2O(g) AHo = -484 kJ 3. Use the following calorimetrically determined enthalpy changes to predict the standard enthalpy change for the reaction of ethene with chlorine gas. C2H4(g) + Cl2(g) → C2H3C1(g) + HCl(g) AHo = ? H2(g) + Cl2(g) → 2HCI(g) AHo = -185 kJ C2H4(g) + HCl(g) → C2H5C11) AHo = -65 kJ C2H3C1(g) + H2(g) → C2H5C14) AH. = -140 kJ

Sodium carbonate reacts with Sulphuric Acid. What is the balance chemical equation for the reaction?

what are the electropositive atoms in complex disodium edetate reaction with Mg

Given the following reaction:

N2 (g) + 3H2 (g) → 2NH3 (g)

How would the rate of change for NH3 compare to the rate of change for N2?

1. What are buffers?

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2. Write equations to show the dissociation of the salts (i) ammonium chloride and (ii) sodium acetate.

I. __________________________________________________________________

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II. __________________________________________________________________

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3. Write equations to show the hydrolysis of the two salts named in Exercise 2.

I. __________________________________________________________________

II. ________________________________________________________________

4. Calculate the pH of the ammonium chloride solution of concentration 0.1M if the acid dissociation constant/ hydrolysis constant for the NH₄⁺ ion is 5.8 x 10^-10