Deck 5: Stoichiometry: Quantitative Information About Chemical Reactions

Question 1

What mass of iron can be produced from the reaction of 175 kg Fe₂O₃ with 385 kg CO?
Fe₂O₃(s)+ 3 CO(g) $\to$ 2 Fe(s)+ 3 CO₂(g)

A) 2.19 kg
B) 30.6 kg
C) 61.2 kg
D) 122 kg
E) 512 kg

Answer 1

122 kg

Question 2

Nitric oxide is made from the oxidation of ammonia.What mass of nitric oxide can be made from the reaction of 8.00 g NH₃ with 17.0 g O₂?
4 NH₃(g)+ 5 O₂(g) $\to$ 4 NO(g)+ 6 H₂O(g)

A) 4.54 g
B) 12.8 g
C) 14.1 g
D) 15.9 g
E) 25.0 g

Answer 2

12.8 g

Question 3

When strongly heated,boric acid breaks down to boric oxide and water.What mass of boric oxide is formed from the decomposition of 15.0 g B(OH)₃?
2 B(OH)₃(s) $\to$ B₂O₃(s)+ 3 H₂O(g)

A) 7.50 g
B) 15.0 g
C) 8.44 g
D) 16.9 g
E) 33.8 g

Answer 3

8.44 g

Question 4

Magnesium reacts with iodine gas at high temperatures to form magnesium iodide.What mass of MgI₂ can be produced from the reaction of 5.15 g Mg and 50.0 g I₂?

A) 29.5 g
B) 44.9 g
C) 54.8 g
D) 55.2 g
E) 58.9 g

Question 5

The complete combustion of 0.32 moles of propane,C₃H₈,will

A) consume 0.32 mol O₂ and produce 0.32 mol CO₂.
B) consume 0.32 mol O₂ and produce 0.64 mol CO₂.
C) consume 1.6 mol O₂ and produce 0.96 mol CO₂.
D) consume 1.6 mol O₂ and produce 4.8 mol CO₂.
E) consume 1.6 mol O₂ and produce 1.3 mol CO₂.

Question 6

Hydrogen peroxide decomposes into oxygen and water.What mass of oxygen is formed from the decomposition of 125 g of H₂O₂?

A) 58.8 g
B) 66.4 g
C) 107 g
D) 118 g
E) 125 g

Question 7

Sulfur dioxide will react with water to form sulfurous acid (see balanced equation below).
SO₂(g)+ H₂O(l) $\to$ H₂SO₃(l)
What mass of sulfur dioxide is needed to prepare 21.06 g of H₂SO₃(l)?

A) 16.44 g
B) 26.98 g
C) 0.3287 g
D) 0.2566 g
E) 21.06 g

Question 8

How many moles of sodium bromide can be produced from the reaction of 1.03 moles of sodium with 0.650 moles of bromine gas?
2 Na(s)+ Br₂(g) $\to$ 2 NaBr(s)

A) 0.650 mol
B) 1.03 mol
C) 1.30 mol
D) 2.06 mol
E) 0.515 mol

Question 9

If 48.8 g of O₂ is mixed with 48.8 g of H₂ and the mixture is ignited,what is the maximum mass of water that may be produced?

A) 439 g
B) 54.9 g
C) 48.8 g
D) 98 g
E) 86.8 g

Question 10

The commercial production of phosphoric acid,H₃PO₄,can be represented by the equation

The molar mass for each reactant is shown $\underline{\text{ below}}$ the reactant,and the mass of each reactant for this problem is given $\underline{\text{ above. }}$ Which substance is the limiting reactant?

A) H₂O
B) C
C) O₂
D) Ca₃(PO₄)₂
E) SiO₂

Question 11

Pure copper may be produced by the reaction of copper(I)sulfide with oxygen gas as follows:
Cu₂S(s)+ O₂(g) $\to$ 2Cu(s)+ SO₂(g)
What mass of copper(I)sulfide is required in order to prepare 0.610 kg of copper metal?

A) 0.610 kg
B) 0.305 kg
C) 0.459 kg
D) 1.53 kg
E) 0.764 kg

Question 12

How many grams of dioxygen are required to completely burn 4.3 g of C₂H₅OH?

A) 19 g
B) 15 g
C) 3.0 g
D) 42 g
E) 58 g

Question 13

If 5.00 g Br₂ and 1.10 g NH₃ react according to the equation below,what is the maximum mass of ammonium bromide produced?

A) 3.06 g
B) 6.13 g
C) 12.9 g
D) 4.74 g
E) 8.43 g

Question 14

How many moles of Mg₃P₂(s)can be produced from the reaction of 0.14 mol Mg(s)with 0.020 mol P₄(s)?
6 Mg(s)+ P₄(s) $\to$ 2 Mg₃P₂(s)

A) 0.047 mol
B) 0.14 mol
C) 0.42 mol
D) 0.020 mol
E) 0.040 mol

Question 15

The compound P₄S₃ is used in matches.It reacts with oxygen to produce P₄O₁₀ and SO₂.The $\underline{\text{unbalanced }}$ chemical equation is shown below.
P₄S₃(s)+ O₂(g) $\to$ P₄O₁₀(s)+ SO₂(g)
What mass of SO₂ is produced from the combustion of 0.401 g P₄S₃?

A) 0.134 g
B) 1.20 g
C) 0.0389 g
D) 0.117 g
E) 0.350 g

Question 16

Calculate the number of moles of O₂ required to react with phosphorus to produce 4.76 g of P₄O₆.
(Molar mass P₄O₆ = 219.9 g/mol)

A) 0.0216 mol
B) 0.149 mol
C) 0.0649 mol
D) 0.0433 mol
E) 0.130 mol

Question 17

If the complete combustion of an unknown mass of ethylene produces 16.0 g CO₂,what mass of ethylene is combusted?
C₂H₄(g)+ 3 O₂(g) $\to$ 2 CO₂(g)+ 2 H₂O(g)

A) 0.182 g
B) 0.364 g
C) 5.10 g
D) 8.00 g
E) 12.6 g

Question 18

Potassium hydrogen carbonate decomposes with heat as follows:
2KHCO₃(s) $\to$ K₂CO₃(s)+ CO₂(g)+ H₂O(l)
How many moles of potassium carbonate will be produced if 201 g of potassium hydrogen carbonate are heated?

A) 1.00 mol
B) 1.45 mol
C) 10.8 mol
D) 101 mol
E) 2.01 mol

Question 19

Aspirin (C₉H₈O₄)is produced by the reaction of salicylic acid (M = 138.1 g/mol)and acetic anhydride

(M = 102.1 g/mol).C₇H₆O₃(s)+ C₄H₆O₃( ) $\to$ C₉H₈O₄(s)+ C₂H₄O₂(
)
If you react 2.00 g C₇H₆O₃ with 1.60 g C₄H₆O₃,what mass of aspirin (M = 180.2 g/mol)can theoretically be obtained?

A) 0.40 g
B) 2.61 g
C) 2.82 g
D) 1.53 g
E) 3.60 g

Question 20

One step in the isolation of pure rhodium metal (Rh)is the precipitation of rhodium(III)hydroxide from a solution containing rhodium(III)sulfate according to the following balanced chemical equation:

Rh₂(SO₄)₃(aq)+ 6NaOH(aq) → 2Rh(OH)₃(s)+ 3Na₂SO₄(aq)

If 6.20 g of rhodium(III)sulfate reacts with excess sodium hydroxide,what mass of rhodium(III)hydroxide may be produced?

A) 3.86 g
B) 12.4 g
C) 6.20 g
D) 0.966 g
E) 7.73 g

Question 21

Aspirin is produced by the reaction of salicylic acid (M = 138.1 g/mol)and acetic anhydride
(M = 102.1 g/mol).C₇H₆O₃(s)+ C₄H₆O₃( ) $\to$ C₉H₈O₄(s)+ C₂H₄O₂(
)
If 2.04 g of C₉H₈O₄ (M = 180.2 g/mol)is produced from the reaction of 3.03 g C₇H₆O₃ and 4.01 g C₄H₆O₃,what is the percent yield?

A) 28.8%
B) 29.0%
C) 50.9%
D) 51.6%
E) 67.3%

Question 22

Complete combustion of a 0.30-mol sample of a hydrocarbon,C_xH_y,gives 1.80 mol of CO₂ and 1.20 mol of H₂O.The molecular formula of the original hydrocarbon is

A) C₃H₈.
B) C₆H₈.
C) C₇H₁₈.
D) C₅H₅.
E) C₅H₆.

Question 23

A 1.850 g mixture of SrCO₃ and SrO is heated.The SrCO₃ decomposes to SrO and CO₂.What was the mass percentage of SrCO₃ in the mixture if the mass after heating is 1.445 g?

A) 26.6%
B) 21.9%
C) 13.7%
D) 73.4%
E) 78.1%

Question 24

Of the following,the only empirical formula is

A) C₆H₁₂.
B) C₂H₈.
C) C₃H₈.
D) H₂O₂.
E) O₃.

Question 25

Sulfur hexafluoride is produced by reacting elemental sulfur with fluorine gas.S₈(s)+ 24 F₂(g) $\to$ 8 SF₆(g)
What is the percent yield if 18.3 g SF₆ is isolated from the reaction of 10.0 g S₈ and 30.0 g F₂?

A) 40.2%
B) 45.8%
C) 47.6%
D) 54.6%
E) 61.0%

Question 26

Chlorine was passed over 2.02 g of heated titanium,and 6.50 g of a chloride-containing compound of Ti was obtained.What is the empirical formula of the chloride-containing compound?

A) TiCl₂
B) TiCl₄
C) TiCl
D) TiCl₃
E) Ti₂Cl₃

Question 27

A compound consists of only C and F.It contains 38.71% C by mass.What is the empirical formula of the compound?

A) CF
B) CF₂
C) CF₃
D) C₂F
E) CF₄

Question 28

Under certain conditions the reaction of ammonia with excess oxygen will produce a 29.5% yield of NO.What mass of NH₃ must react with excess oxygen to yield 157 g NO?
4 NH₃(g)+ 5 O₂(g) $\to$ 4 NO(g)+ 6 H₂O(g)

A) 89.1 g
B) 302 g
C) 263 g
D) 26.3 g
E) 938 g

Question 29

A 3.361 g sample of a hydrocarbon is burned in an excess of dioxygen,producing 6.295 g CO₂ and 3.866 g H₂O.What is the empirical formula of the hydrocarbon?

A) CH₃
B) CH₂
C) C₂H₃
D) CH₄
E) CH

Question 30

A 5.95-g sample of AgNO₃ is reacted with excess BaCl₂ according to the equation
2AgNO₃(aq)+ BaCl₂(aq) $\to$ 2AgCl(s)+ Ba(NO₃)₂(aq)
To give 3.75 g of AgCl.What is the percent yield of AgCl?

A) 49.8 %
B) 37.4 %
C) 74.7 %
D) 63.0 %
E) 100 %

Question 31

A certain compound has a molar mass of 150 g/mol.Which is a possible empirical formula for this compound?

A) CH₂O
B) CHO
C) C₂H₂O₂
D) C₂HO
E) C₂H₂O

Question 32

The empirical formula of ethylene is CH₂.An experimental determination of the molar mass of ethylene yields the value of 28 g/mol.What is the $\underline{\text{ molecular }}$ formula of ethylene?

A) C₅H₁₀
B) CH₂
C) C₂H₄
D) C₃H₈
E) C₆H₉

Question 33

The reaction of 11.9 g of CHCl₃ with excess chlorine produced 10.3 g of CCl₄,carbon tetrachloride:

2CHCl₃ + 2Cl₂ $\to$ 2CCl₄ + 2HCl
What is the percent yield?

A) 86.6 %
B) 100 %
C) 67.2 %
D) 33.6 %
E) 44.8 %

Question 34

A 2.841 g sample of a hydrocarbon is burned in an excess of dioxygen,producing 7.794 g CO₂ and water.What mass of hydrogen is contained in the original sample?

A) 0.7140 g
B) 4.953 g
C) 10.64 g
D) 2.826 g
E) 1.421 g

Question 35

Consider the fermentation reaction of glucose:
C₆H₁₂O₆ $\to$ 2C₂H₅OH + 2CO₂
A 1.00-mol sample of C₆H₁₂O₆ was placed in a vat with 100 g of yeast.If 67.8 g of C₂H₅OH was obtained,what was the percent yield of C₂H₅OH?

A) 73.6 %
B) 36.8 %
C) 67.8 %
D) 100 %
E) none of these

Question 36

Nitric oxide,NO,is made from the oxidation of NH₃ as follows:
4NH₃ + 5O₂ $\to$ 4NO + 6H₂O
If 9.4-g of NH₃ gives 12.0 g of NO,what is the percent yield of NO?

A) 91 %
B) 44 %
C) 17 %
D) 72 %
E) 22 %

Question 37

If 15.0 g N₂ and 2.00 g H₂ react to produce 1.38 g NH₃,what is the percent yield of the reaction?
N₂(g)+ 3 H₂(g) $\to$ 2 NH₃(g)

A) 7.57%
B) 12.2%
C) 8.12%
D) 15.1%
E) 8.17%

Question 38

Sulfur trioxide,SO₃,is made from the oxidation of SO₂as follows: 2SO₂ + O₂ $\to$ 2SO₃
A 21-g sample of SO₂ gives 18 g of SO₃.The $\underline{\text{ percent yield }}$ of SO₃ is .

A) 11 %
B) 69 %
C) 17 %
D) 26 %
E) 100 %

Question 39

Pure copper may be produced by the reaction of copper(I)sulfide with oxygen gas as follows:
Cu₂S(s)+ O₂(g) $\to$ 2Cu(s)+ SO₂(g)
If the reaction of 0.630 kg of copper(I)sulfide with excess oxygen produces 0.190 kg of copper metal,what is the percent yield?

A) 75.5 %
B) 39.9 %
C) 30.2 %
D) 151 %
E) 37.8 %

Question 40

The reaction of 0.779 g K with O₂ forms 1.417 g potassium superoxide,a substance used in self-contained breathing devices.Determine the formula for potassium superoxide.

A) KO₂
B) KO
C) K₂O₃
D) K₂O
E) KO₄

Question 41

What volume of 2.52 M HCl is required to prepare 176.5 mL of 0.449 M HCl?

A) 9.91 $\times$ 10² mL
B) 1.56 $\times$ 10² mL
C) 31.4 mL
D) 0.0318 mL
E) 2.00 $\times$ 10² mL

Question 42

Naphthalene,a hydrocarbon,has an approximate molar mass of 128 g/mole.If the combustion of 0.6400 g naphthalene produces 0.3599 g H₂O and 2.1977 g CO₂,what is the molecular formula of this compound?

A) C₈H₃₂
B) C₉H₁₈
C) C₉H₂₀
D) C₁₀H₈
E) C₁₁H₇

Question 43

A mass of 0.4113 g of an unknown acid,HA,is titrated with NaOH.If the acid reacts with 28.10 mL of 0.1055 M NaOH(aq),what is the molar mass of the acid?

A) 2.965 $\times$ 10^-3 g/mol
B) 9.128 g/mol
C) 138.7 g/mol
D) 337.3 g/mol
E) 820.7 g/mol

Question 44

The pH of a vinegar solution is 4.15.What is the H₃O⁺ concentration of the solution?

A) 7.1 $\times$ 10^-5 M
B) 1.6 $\times$ 10^-2 M
C) 0.62 M
D) 1.4 M
E) 1.4 $\times$ 10⁴ M

Question 45

How many moles of sulfate ions are there in a 0.387-L solution of 0.927 M Al₂(SO₄)₃?

A) 0.359 mol
B) 1.08 mol
C) 1.25 mol
D) 0.120 mol
E) 7.19 mol

Question 46

An aqueous nitric acid solution has a pH of 2.15.What mass of HNO₃ is present in 20.0 L of this solution?

A) 0.11 g
B) 0.022 g
C) 3.7 g
D) 6.8 g
E) 8.9 g

Question 47

What minimum mass of copper (II)nitrate must be added to 30.0 mL of a 0.0387 M phosphate solution in order to completely precipitate all of the phosphate as solid copper (II)phosphate?
2PO₄^3-(aq)+ 3Cu(NO₃)₂(aq) $\to$ Cu₃(PO₄)₂(s)+ 6NO₃^-(aq)

A) 0.218 g
B) 0.653 g
C) 0.145 g
D) 0.0726 g
E) 0.327 g

Question 48

A dilute solution is prepared by transferring 45.00 mL of a 0.5616 M stock solution to a 400.0 mL volumetric flask and diluting to mark.What is the molarity of this dilute solution?

A) 0.06318 M
B) 0.1264 M
C) 0.04992 M
D) 0.01580 M
E) 0.2808 M

Question 49

Polyethylene is a polymer consisting of only carbon and hydrogen.If 2.300 g of the polymer is burned in oxygen it produces 2.955 g H₂O and 7.217 g CO₂.What is the empirical formula of polyethylene?

A) CH
B) CH₂
C) C₂H₃
D) C₅H₈
E) C₇H₈

Question 50

Zn reacts with hydrochloric acid.
Zn(s)+ 2 HCl(aq) $\to$ ZnCl₂(aq)+ H₂(g)
What volume of 3.05 M HCl(aq)will react with 25.0 g Zn(s)?

A) 0.251 L
B) 4.01 L
C) 0.125 L
D) 0.0627 L
E) 2.33 L

Question 51

A 4.541 g sample of a compound containing only carbon,hydrogen,and oxygen is burned in an excess of dioxygen,producing 8.674 g CO₂ and 5.328 g H₂O.What is the empirical formula of the compound?

A) CHO
B) C₂H₆O
C) C₃H₆O
D) C₃H₄O
E) C₃H₈O₃

Question 52

What is the pH of 5.3 $\times$ 10^-3 M HCl(aq)?

A) -1.01
B) 2.28
C) 3.50
D) 1.01
E) 5.65

Question 53

The pH of an aqueous NaOH solution is 12.83.What is the hydrogen ion concentration of this solution?

A) 1.5 $\times$ 10^-13 M
B) 6.7 $\times$ 10^-2 M
C) 1.2 M
D) 6.7 $\times$ 10¹² M
E) 2.7 $\times$ 10^-6 M

Question 54

What is the molarity of an NaI solution that contains 5.3 g of NaI in 41.0 mL of solution?

A) 0.86 M
B) 0.035 M
C) 0.0077 M
D) 0.00027 M
E) 0.13 M

Question 55

A 1.185 g sample of a compound containing only carbon,hydrogen,and oxygen is burned in an excess of dioxygen,producing 2.264 g CO₂ and 1.390 g H₂O.What mass of oxygen is contained in the original sample?

A) 0.4117 g
B) 0.5673 g
C) 1.079 g
D) 0.8733 g
E) 0.2053 g

Question 56

Soft drink bottles are made of polyethylene terephthalate (PET),a polymer composed of carbon,hydrogen,and oxygen.If 1.9022 g PET is burned in oxygen it produces 0.6585 g H₂O and 4.0216 g CO₂.What is the empirical formula of PET?

A) CHO
B) CH₇O₅
C) C₅H₇O
D) C₈H₁₀O
E) C₁₀H₈O₅

Question 57

In order to dilute 35.5 mL of 0.533 M HCl to 0.100 M,the volume of water that must be added is

A) 28.8 mL.
B) 6.66 mL.
C) 1.89 $\times$ 10² mL.
D) 1.50 $\times$ 10^-3 mL.
E) 1.54 $\times$ 10² mL.

Question 58

The combustion of 0.0272 mole of a hydrocarbon produces 1.9609 g H₂O and 3.5927 g CO₂.What is the molar mass of the hydrocarbon?

A) 16.0 g/mol
B) 30.1 g/mol
C) 44.1 g/mol
D) 72.2 g/mol
E) 92.1 g/mol

Question 59

What volume of 0.464 M Na₂CO₃ solution contains 74.7 g of Na₂CO₃?

A) 0.327 L
B) 1.71 $\times$ 10⁴ L
C) 1.52 L
D) 3.67 $\times$ 10³ L
E) 0.658 L

Question 60

What mass of Na₂CO₃ is present in 0.250 L of a 0.852 M Na₂CO₃ solution?

A) 22.6 g
B) 26.5 g
C) 90.3 g
D) 31.1 g
E) 361 g

Question 61

The percent yield of a chemical reaction is calculated by dividing the actual yield by the ________ yield and multiplying by 100%.

Question 62

A 50.00-mL sample of a weak monoprotic acid is titrated with 0.0955 M NaOH.At the endpoint,it is found that 32.56 mL of titrant was used.What was the concentration of the weak acid?

A) 0.0622 M
B) 3.11 M
C) 0.0955 M
D) 5.87 $\times$ 10^-5 M
E) 0.147 M

Question 63

A solution of sodium oxalate (Na₂C₂O₄)in acidic solution is titrated with a solution of potassium permanganate (KMnO₄)according to the following balanced chemical equation:

2KMnO₄(aq)+ 8H₂SO₄(aq)+ 5Na₂C₂O₄(aq) $\to$ 2MnSO₄(aq)+ 8H₂O(l)+ 10CO₂(g)+ 5Na₂SO₄(aq)+ K₂SO₄(aq)

What volume of 0.0388 M KMnO₄ is required to titrate 0.134 g of Na₂C₂O₄ dissolved in 20.0 mL of solution?

A) 1.38 mL
B) 3.45 mL
C) 10.3 mL
D) 25.8 mL
E) 20.0 mL

Question 64

The numbers preceding the formulas in chemical equations are referred to as the ________ coefficients.

Question 65

If 0.1800 g of impure soda ash (Na₂CO₃)is titrated with 15.66 mL of 0.1082 M HCl,what is the percent purity of the soda ash?
Na₂CO₃(aq)+ 2 HCl(aq) $\to$ 2 NaCl(aq)+ H₂O( )+ CO₂(g)

A) 17.96%
B) 49.89%
C) 50.11%
D) 94.13%
E) 99.77%

Question 66

In combustion analysis,the gases produced by the combustion of a hydrocarbon are passed through a tube containing finely divided NaOH supported on asbestos.The purpose of the NaOH is to absorb ________ produced by the combustion reaction.

Question 67

An unknown diprotic acid (H₂A)requires 44.39 mL of 0.111 M NaOH to completely neutralize a 0.580 g sample.Calculate the approximate molar mass of the acid.

A) 406 g/mol
B) 235 g/mol
C) 118 g/mol
D) 59 g/mol
E) 203 g/mol

Question 68

The pH of purified water (or of a neutral solution)is _____.

Question 69

An impure sample of benzoic acid (C₆H₅COOH,122.12 g/mol)is titrated with 0.8067 M NaOH.A 5.109-g sample requires 36.97 mL of titrant to reach the endpoint.What is the percent by mass of benzoic acid in the sample?

C₆H₅COOH(aq)+ NaOH(aq) $\to$ NaC₆H₅COO(aq)+ H₂O(l)

A) 0.02442 %
B) 2.982 %
C) 100.0 %
D) 24.42 %
E) 71.29 %

Question 70

The reaction of 5.07 g N₂ with 0.722 g H₂ produces 1.27 g NH₃.The percent yield of this reaction is ________.

Question 71

PCl₃ can be produced from the reaction of P₄ with Cl₂.
P₄(s)+ 6 Cl₂(g) $\to$ 4 PCl₃(g)
If 1.00 g P₄ reacts with 1.00 g Cl₂,which reactant is the limiting reactant? What mass of product may be produced?

Question 72

Which of the following statements is/are CORRECT?
1)Absorbance is directly proportional to the intensity of the incident light.
2)Absorbance is inversely proportional to the analyte concentration.
3)Absorbance is directly proportional to the path length of the light.

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3
E) 1,2,and 3

Question 73

The reaction of HCl with NaOH is represented by the equation
HCl(aq)+ NaOH(aq) $\to$ NaCl(aq)+ H₂O(l)
What volume of 0.686 M HCl is required to titrate 42.8 mL of 0.334 M NaOH?

A) 9.81 mL
B) 1.46 mL
C) 20.8 mL
D) 42.8 mL
E) 87.9 mL

Question 74

The following equation: A = $\varepsilon$$\times$
$\times$ C (where
is path length and C is concentration)is known as the _____-Lambert law.

Question 75

Transmittance,T,is defined as the intensity of light transmitted through a sample divided by the intensity of light incident on the sample.The absorbance,A,is defined as

A) A = -log T
B) A = log (-T)
C) A = 10^T
D) A = 10^-T
E) A = 10^-1/T

Question 76

Calibration of a spectrophotmeter using a series of green dye containing solutions provides a set of data which follows the Beer-Lambert Law,with a trendline of y = 1.070 $\times$ 10³x (y-axis = absorbance,x-axis = molar concentration).What is the molar concentration of a solution with an absorbance of 0.3131?

A) 0.2926 M
B) 0.3131 M
C) 3.194 M
D) 0.9346 M
E) 0.6869