A) gas B) solid C) salts D) ice E) liquid 3. A small amount of salt dissolved in water is an example of a __________. A) compound B) solid C) heterogeneous mixture D) pure substance E) homogeneous mixture 4. Which of the following is an illustration of the law of constant composition? A) Water is 11% hydrogen and 89% oxygen by mass.
1 / [CO2] C. [CaO][CO2] / [CaCO3] D. [CaCO3] / [CaO][CO2] _____ 13. The value of Kp for the reaction 2 NO2 (g) [pic] N2O4 (g) is 1.52 at 319 K. What is the value of Kp at this temperature for the reaction N2O4 (g) [pic] 2 NO2 (g) ? A. -1.52 B. 1.23 C. 5.74 X 10-4 D. 0.658 _____ 14.
The density is 6.67 × 10-4 g/cm3. e. It dissolves slightly in water. c. Carbon dioxide forms when it burns. ____ 4. Which of these physical changes would require the liberation of energy?
Pb (NO3) 2 10. A compound is 42.3 % C, 5.94 % H, 32.9 % N, and 18.8 % O and has a molecular mass of 425.25 g/mol. Calculate the empirical and molecular formula. C15H25N10O5 11. How many moles of Al2O3 are produced by the reaction 200. g Al?
In forming covalent bonds where the octet rule is obeyed, sulfur usually forms ________ bonds and chlorine usually forms ________ bonds. A) one; one B) two; two C) one; two D) two; one E) six; seven 6. The number of valence electrons in the acetic acid molecule (CH3CO2H) is ________. A) 0 B) 8 C) 16 D) 24 E) 32 7. A molecule in which the central atom forms three single bonds and has one lone pair is said to have a ________ shape.
54Cr 24 g. 52Cr 24 f. e. 14C 6 d. 50Cr 24 c. 12C 6 b. 63Cu 29 a. 17O 8 Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc. Chemistry: Matter and Change • Chapter 4 Mass contribution ( ؍mass)(percent abundance) For 27X: (27.977 amu)(92.23%) 08.52 ؍amu For 28X: (28.976 amu)(4.67%) 53.1 ؍amu For 29X: (29.974 amu)(3.10%) 929.0 ؍amu Atomic mass of X 08.52 ؍amu ؉ 1.35 amu ؉ 0.929 amu 80.82 ؍amu The element is silicon. Mass (amu) Isotope element. Show all your work.
57 (1) (iii) A triglyceride is also formed in the reaction between glycerol and three molecules of oleic acid, C17H33COOH. State and explain which of the two triglycerides (the one formed from stearic acid or the one formed from oleic acid) has the higher melting point. (the one from) stearic acid; saturated / no (C to C) double bonds; chains pack close together / stronger intermolecular forces / van der Waals’ forces etc; 3 Ignore hydrogen bonding. If wrong choice made, only third mark can be scored. (3) (b) An oil sample containing 0.0100 mol of oil was found to react with 7.61 g of iodine, I2.
This reaction can be summed up using the following formula: 5Fe2++8H++MnO4- →5Fe3++Mn2++4H2O After standardization, the potassium permanganate solution is then titrated with 3 different magnesium oxalate solutions. To find the concentration of the C2O42- the balanced net ionic redox reaction formula is used: 5C2O42-+16H++2MnO4- →10CO2+2Mn2++8H2O It is important to note the addition of sulfuric acid (9M H2SO4) in performing this experiment because of the following reasons: 1) Sulfuric acid keeps the iron (II) from air oxidizing into iron (III) 2) Sulfuric acid keeps the iron (II) from hydrolyzing into Fe(OH)2 3) Sulfuric
25 cm3 of a solution of sodium hydroxide reacts with 15 cm3 of 0.1 mol/dm3 HCl. What is the molar concentration of the sodium hydroxide solution? 4. Succinic acid has the formula (CH2)n(COOH)2 and reacts with dilute sodium hydroxide as follows: (CH2)n(COOH)2 + 2NaOH → (CH2)n(COONa)2 + 2H2O 2.0 g of succinic acid were dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 18.4 cm3 was required to neutralise 25 cm3 of 0.1 moldm-3 NaOH.
Volume of gas = molar volume x number of moles The molecular formula of gaseous hydrocarbons (CxHy) and organic compounds (CxHyOz) can be determined by combustion in excess oxygen to form carbon dioxide and water, using the following equations: CxHy + (x+ y/4) O2 x CO2 + y/2 H2O CxHyOz + (x+ y/4- z/2) O2 x CO2 + y/2 H2O Example 4 When 10 cm3 of a gaseous hydrocarbon was combusted in excess oxygen in an enclosed vessel, the volume of gas (measured at 298K) was reduced by 25 cm3. The addition of excess NaOH (aq) caused a further reduction in gas volume of 40 cm3 (measured at 298 K). The pressure in the vessel was maintained constant at 1 atm throughout the measurements. Find the molecular formula of the