(Chemistry subject) - Assignment Example

Assignment Chapter Molecular Reasons 14- What is the difference between a homogeneous and a mixture and a heterogeneous mixture? Give one example of eachAnswer: Mixture: This is a mixture of two or more pure substance combined to form a mixture. It can consist of Matter having variable composition with definite or varying properties and can be separated into component elements or compounds. Example include carbonated soda, coarse mixture of sea water or even mixture of air that contain nitrogen, oxygen, carbon dioxide and many others.

Homogeneous Mixture: They possess uniform composition and look. They include salt and water, soda, metallic alloys.Heterogeneous Mixture: They do not have uniform composition such as coarse sand and iron filling mixture22- Categorize either as a law or theory.a- In a chemical reaction, energy is neither created nor destroyed Answer: Lawb- All matter is composed of atomsAnswer: Theoryc- The temperature of a gas increases, with the increase in volume of the gasAnswer: Lawd- Gases are composed of particles in constant motionAnswer: Law26- Which substance is a solid?

Answer: Dry ice30- Classify either as chemical or physical changea- The burning of butane in a lighterAnswer: Chemicalb- The freezing of waterAnswer: Physicalc- The bending of a copper rodAnswer: Physicald- The fading of a brightly colored cloth upon excessive exposure to sunlightAnswer: Chemical34- Determine if any of the following data sets on chemical reactions are not consistent with the conservation of mass law and, therefore, erroneousa- 8 grams of natural gas react with 38 grams of oxygen gas, to form 17 grams of carbon dioxide and 19 grams of waterAnswer: Yes, it is inconsistent because the mass is not the same in this data set which directly contradicts the law of conservation of mass.b- 5.7 grams of sodium react with 8.

9 grams of chlorine, to produce 14.6 grams of sodium chloride Answer: No, because the data set is okay and no mass has been change thus the conservation of mass law is consistent.36- A chemist combines 6 grams of hydrogen with 52 grams of oxygen in a reaction that results in water as its only product. 4 grams of oxygen remain while all the hydrogen reacts. How many grams of water are formed? Answer: 6g h + 52g O =54g H2O 58g – 4g = 54g of water (law of conservation of mass) Chapter 2- The chemist’s toolbox16- Express each of the following in scientific notation:a- 19,541,453 (population of New York state)Answer: 1.

9541453 * 10^7b- 6,873,370,698 (world population)Answer: 6.873370698 * 10^9c- 0.00000000007461 m (length of a hydrogen-hydrogen chemical bond)Answer: 7.461 * 10^-11d- 0.000015 m (diameter of a human hair)Answer: 1.5 *10^-518- Express each of the following in decimal notation:a- 6.022*10^23 (number of carbon atoms in 12.01 grams of carbon)Answer: 602200000000000000000000 b- 3.00*10^8 m/s (speed of light)Answer: 300000000 m/sc- 450*10^(-9) m (wavelength of blue light)Answer: 0.000000045 md- 13.7*10^9 years (approximate age of the universe)Answer: 13700000000 years20- The distance from New York to Los Angeles is 2777 miles.

Convert this distance into each of the following units:a- KilometersAnswers: 2777 miles * 0.6214/1 = 1725.6278kmb- MetersAnswer: 1725627.8 mc- FeetAnswer: 3652.58 feet26- Perform each of the following conversions within the metric system:a- 2319cm to mAnswer: 2319cm * 1/100 = 23.19mb- 4912.5 g to KgAnswer: 4.9125 Kgc- 23.1cm to mmAnswer: 231mmd- 561ml to L = 1000ml is equal to 1LAnswer: 0.561 L28- Perform the following conversions between the metric and English system:a- 4.92 in. to mmAnswer: 124.

968 mmb- 8779yds. to KmAnswer: 8.02752 Kmc- 87ft. to mAnswer: 26.5176 md- 3.8 in to cmAnswer: 1 inch is equal to 2.54cm Therefore, 3.8 * 2.54 = 9.652cm38- (Please see image from my textbook that I sent the writer, thanks)Answer: a- Total increase = Maximum increase – Minimum increase 382 -308 = 74ppmb- Average yearly increase from 1950 to 2001(not up to 2007)Total number of years = 51yrs.Total increase = 74ppm…. 74ppm/51yrs = 1.45ppm/yr.c- Total percentage increase.

Max increase = 382 ppmInitial level = 308 ppm = 308/382ppm * 100% = 80.6 %d- The yearly percentage increaseTotal percentage increase / Total years = 80%/51yrs = 1.6% per year42- A 3.80ml sample of mercury has a mass of 51.4 g. What is the density of mercury in g/cm^3?Answer: Formulae of density = mass/ volume 51.4g/3.8cm3 = 13.53g/cm3NOTE: 1ml = 1 cm344- A thief plans to steal a bar of gold from a woman’s purse and replace it with a bag of sand.

Assume that the volumes of gold and the sand are 350ml each and that the density of sand is 3.00 g/cm^3a- Calculate the mass of each objectAnswer: Formulae mass = volume * density = 350cm3*3.00g/cm3 = 1050g NOTE: 1cm3 = 1mlb- Would the woman notice a difference in the weight of her purse?Answer: yes because mercury has a bigger density than sandWorks CitedTro, Nivaldo J. Chemistry in Focus: A Molecular View of our World. 2012: Cengage Learning, New York. Print.