Get college assignment help at uniessay writers 55.0 calories of heat are added to a small lead block. If the temperature of the lead increases from 27.0°C to 59.2°C, what must be the mass of the lead block?
An unreactive,, gaseuos element that is a product of the nuclear reaction of hydrogen atoms. This reaction occred at the beginning of time and occurs today in stars such as our sun.The second most abundant element in the universe, it is quite rare on Earth. Small concentrations are found in some natural gas deposits. It is also used in blimps because of its low density. Its is also used in cryogenic work because it can be compressed to a liquid that has a temperature of 269 celsius. What is this element?
Calculate the H for the reaction when 50.0 mL of 0.500 M aqueous sodium hydroxide solution at 25.0°C reacts with 50.0 mL of 0.500 M HCl at 25.0°C in a coffee cup calorimeter. The temperature of the resultant solution increases from 28.2°C. Assume that the resultant solution has the same density and specific heat as liquid water, i.e., 4.18 J/g°C
Which one of the following is a redox reaction? 2Na(g) Cl2(g) → 2NaCl(s) Ba2 (aq) SO42-(aq) → BaSO4(s) K2Cr2O7(aq) 2KOH(aq) → 2K2CrO4(aq) H2O(l) Na2CO3(s) 2HCl(aq) → 2NaCl(aq) CO2(g) H2O(l) H2O(l) → H (aq) OH-(aq)
CuBr2 and KOH. What is the balanced net precipitation reaction for this mixture?
How many atoms of carbon are there in 0.40 mole of procaine, C13H20N2O2, a “pain killer” used by dentists?
If 5.4 kcal of heat is added to 1.00 kg of water at 100 degrees celsius, how much steam at 100 degrees is produced? Please show your work for your answer.
After heating the crucible is set on the lab bench where it is contaminated with the cleaning oil used to clean the lab bench but before its mass is measured.The analysis continues where the mass of the anhydrous salt is determined.While heating, the cleaning oil is burned off the bottom of the crucible. Describe the error that has occured; that is , is the mass of the anhydrous salt remaining in the crucible reported as being too high or low? Explain.
A portable electric water heater transfers 255 watts of power to 5.5L of water, where 1W=1J/s. How much time (in minutes) will it take for the water heater to heat the 5.5L of water from 28C to 42C? (Assume that the water has a density of 1.0g/mL)
Carbon tetrachloride melts at 250 K. The vapor pressure of the liquid is 10539 Pa at 290 K and 74518 Pa at 340 K. The vapor pressure of the solid is 270
Get college assignment help at uniessay writers what are the normal freezing points and boiling points of the following solutions? a) 20.7 g NaCl in 135 mL of water. (Assume the van’t Hoff factor (i) is equal to 1.8) b) 14.9 g of Urea [(NH2)2CO] in 63.5 mL of water. A solution is prepared by condensing 4.27 L of a gas, measured at 29.0C and 739 mmHg pressure, into 83.1g of benzene. Calculate the freezing point of this solution. The solubility of oxygen in freswater at 25C and 1.0 atm is around 0.00026 mol/L. Calculate the Henry’s law constant for oxygen solubility in freshwater under these conditions. (The partial pressure of oxygen at 1.0 atm of atmospheric pressure is 0.20 atm.) The density of an aqueous solution containing 21.0 percent of ethanol (C2H5OH) by mass is 0.968 g/mL. a) calculate the molality of this solution. b) calculate its molarity. c) what volume of the solution would contain 0.240 mole of ethanol? A solution made from 6.50g of an unknown compound in 27.8g of diphenyl gave a freezing-point depression of 1.56C. Calculate the molality of the solution. (Kf for diphenyl is 8.00C/m.) Calculate the molality of each of the following aqueous solutions. a) 3.15 M NaCl solution (density of solution = 1.08 g/mL). b) 39.8 percent by mass KBr solution.
Calculate the hydrogen ion concentration for an aqueous solution that has a pH of 3.45. 1. 0.54 M 2. 2.8 × 10−11 M 3. 3.5 × 10−4 M correct 4. 1.22 M 5. 3.2 × 10−2 M
Given the following pKa values, rank the conjugate bases in order of increasing strength. I) HF pKa = 3.45 II) HCN pKa = 9.31 III) HNO2 pKa = 3.37 IV) HCOOH pKa = 3.75 V) H2CO3 pKa = 6.37 1. II, V, IV, I, III 2. I, II, III, IV, V 3. II, IV, V, III, I 4. V, III, I, II, IV 5. III, I, IV, V, II
How many moles of carbon are needed to react with 500g of hematite
Consider the ionization constants hypochlorous acid (HOCl) : Ka = 3.5×10^−8; ammonia (NH3) : Kb = 1.8×10^−5. A solution of ammonium hypochlorite (NH4OCl) is 1. basic, because the cation hydrolyzes to a greater extent than the anion. 2. neutral, because the anion hydrolyzes to a greater extent than the cation. 3. neutral, because the cation and the anion hydrolyze to the same extent. 4. acidic, because the anion hydrolyzes to a greater extent than the cation. 5. neutral, because NH4OCl is a weak base/weak acid salt. 6. acidic, because the cation hydrolyzes to a greater extent than the anion. 7. basic, because the cation and the anion hydrolyze to the same extent. 8. acidic, because the cation and the anion hydrolyze to the same extent. 9. basic, because the anion hydrolyzes to a greater extent than the cation. 10. neutral, because the cation hydrolyzes to a greater extent than the anion. show all works
What is the daughter nucleus produced when 227Th undergoes alpha decay?
Zinc metal reacts with hydrochloric acid according to the following equation: Zn 2HCl –> ZnCl2 H2. How many grams of hydrogen gas can be obtained if 50.0 g of zinc react completely?
A gas has a volume of 4.00 L at 0°C. What final temperature in degrees Celsius is needed to cause the volume of the gas to change to the following, if n and P are not changed?
an adult person radiates heat to the surroundings at about the same time as a 100-watt lightbulb. what is the total amount of energy in kcal radiated to the surroundings by an adult in 24 hrs?
1. Use the paper cup during this part of the experiment. 2. Measure out 25.0 mL of vinegar and pour into the cup. 3. Measure out 1/2 tsp. of baking soda using a piece of paper towel to hold the baking soda. In the data table below, record the amount of baking soda used. 4. Add the baking soda to the vinegar slowly. Don’t let the bubbles overflow the cup. Observe the reaction and record in the data table. 5. Before moving on to Part 2, answer the analysis questions for Part 1. Data Table Part 1 Amount of vinegar Amount of baking soda Observations of reaction Part 2: Conserving Mass 1. You may use any of the listed materials for this part of the procedure. If you were to mass the contents before and after the reaction, you would notice that the mass was less after the reaction than before. 2. Based on your answer to #2 in the Part 1 analysis questions, devise a method for repeating the experiment without losing any mass. Use the same amount of reactants, but you may use the different items from the materials list. Part 2 of the analysis questions will ask you to write the procedure that you used. Analysis Part 1 Consider all that happened during your experiment. 1. Did mass appear to be conserved during this chemical reaction? **Use complete sentences for your answer. Yes or No is not an acceptable answer.** 2. If you could determine the mass of the reactants before and after the reaction, you would find that the mass decreased after the reaction. Based on your observations, where did the extra mass go? ***Remember that mass cannot be created or destroyed. It just does not disappear. Mass is simply rearranged and can even change form (solid, liquid, gas, etc.) Analysis Part 2 1. Describe how you performed the procedure in Part 2. Use a numbered procedure as your description. Be specific. 2. Describe how your experiment might prove that mass was conserved.
A piece of sodium metal reacts completely with water as follows: 2Na(s) 2H2O(l) 2NaOH(aq) H2(g) The hydrogen gas generated is collected over water at 25.0 °C. The volume of the gas is 246 mL measured at 1.00 atm. Calculate the number of grams of sodium used in the reaction. (Vapor pressure of water at 25°C = 0.0313 atm.)
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