Explain (giving at least one example) how stable isotopes of oxygen (i.e. 16O and 18O) can be used to measure the paleotemperature of the ocean, specifically based on calcium carbonate in “shells?”
In: Chemistry
Enough of a monoprotic weak acid is dissolved in water to produce a 0.0122 M solution. The pH of the resulting solution is 2.64 . Calculate the Ka for the acid.
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In a 1.0× 10–4 M solution of HClO(aq), identify the relative molar amounts of these species from least to most. HNO3, OH^-,H3O^+,NO3^-,H2O
In: Chemistry
Use the balanced equation for the combustion of ethane
to complete the table.
| 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g) |
| Initially mixed |
0.231 g | 1.056 g | 0.00 g | 0.00 g |
| How much reacts |
g | g | ― | ― |
| Composition of final mixture |
g | g | g | g |
In: Chemistry
1) The percent ionization of a certain weak acid is 3.14%. If the starting concentration of the acid is 0.55 M, what is the Ka of the acid?
2) What is the pH of a buffer made by mixing 575 mL of 0.150 M potassium acetate with 450 mL of 0.225 M acetic acid (Ka = 1.8 × 10^–5 )?
In: Chemistry
3. Liquid Coffee Mate has many ingredients including corn syrup solids, vegetable oil, and sodium caseinate (a milk derivative). Classify each of these substances into the following categories of macromolecules: carbohydrates, lipids, or proteins. Which substance(s) is/are responsible for the result you obtained with the biuret reagent?
4. Research the substance pepsin. What is it used for? If you were to test the enzyme amylase, what result would you expect with the biuret reagent? Why?
5. You enjoy the following snack one afternoon: a can of Pepsi, pretzels, and sliced apples with peanut butter. Would any of these four food items yield a positive result with biuret reagent? If so, which one(s) and why?
In: Chemistry
Determine the pH during the titration of 24.8
mL of 0.475 M nitrous acid
(Ka = 4.5×10-4) by
0.361 M NaOH at the following
points.
(a) Before the addition of any NaOH
__________
(b) After the addition of 8.20 mL of
NaOH __________
(c) At the half-equivalence point (the titration midpoint)
________
(d) At the equivalence point __________
(e) After the addition of 48.9 mL of
NaOH __________
In: Chemistry
Carbon-14 decays as follows:
14 0 14
C ----> e + N
6 -1 7
isotopic masses are 14.00307 for nitrogen-14 and 14.00324 for carbon-14. What energy change (kJ/moles) occurs in the beta decay of C-14? NOTE: Do I use these two masses to get the mass defect or do I use the mass of protons and nuetrons to find the mass defect of each one and then subtract the two?
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Give representative chemical formulas for the three principal types of fossil fuels.
Write a balanced chemical reaction converting each fuel to CO2 and water.
Using the equation calculate the grams of CO2 emitted per gram of fuel burned.
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Calculate the enthalpy of the reaction
2NO(g)+O2(g)?2NO2(g)
given the following reactions and enthalpies of formation:
12N2(g)+O2(g)?NO2(g), ?H?A=33.2 kJ
12N2(g)+12O2(g)?NO(g), ?H?B=90.2 kJ
Express your answer with the appropriate units.
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| ?H? = |
Part B
Calculate the enthalpy of the reaction
4B(s)+3O2(g)?2B2O3(s)
given the following pertinent information:
B2O3(s)+3H2O(g)?3O2(g)+B2H6(g), ?H?A=+2035 kJ
2B(s)+3H2(g)?B2H6(g), ?H?B=+36 kJ
H2(g)+12O2(g)?H2O(l), ?H?C=?285 kJ
H2O(l)?H2O(g), ?H?D=+44 kJ
Express your answer with the appropriate units.
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| ?H? = |
In: Chemistry
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Solid carbon can react with gaseous water to form carbon monoxide gas and hydrogen gas. The equilibrium constant for the reaction at 700.0 K is 1.6×10−3 Kp . |
Part A If a 1.55-LL reaction vessel initially contains 140 torr of water at 700.0 KK in contact with excess solid carbon, find the percent by mass of hydrogen gas of the gaseous reaction mixture at equilibrium.
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In: Chemistry
i want a definition on lipids trans fats and hydrogenation what they do and there formulas
In: Chemistry
1. When a solid dissolves in water, heat may be evolved or absorbed. The heat of dissolution (dissolving) can be determined using a coffee cup calorimeter. In the laboratory a general chemistry student finds that when 11.14 g of CsBr(s) are dissolved in 119.50 g of water, the temperature of the solution drops from 22.60 to 19.51 °C. The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.61 J/°C. Based on the student's observation, calculate the enthalpy of dissolution of CsBr(s) in kJ/mol. Assume the specific heat of the solution is equal to the specific heat of water. ΔHdissolution = kJ/mol
2. When a solid dissolves in water, heat may be evolved or absorbed. The heat of dissolution (dissolving) can be determined using a coffee cup calorimeter. In the laboratory a general chemistry student finds that when 11.83 g of CsCl(s) are dissolved in 115.50 g of water, the temperature of the solution drops from 22.20 to 19.26 °C. The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.51 J/°C. Based on the student's observation, calculate the enthalpy of dissolution of CsCl(s) in kJ/mol. Assume the specific heat of the solution is equal to the specific heat of water. ΔHdissolution = kJ/mol
In: Chemistry
Determine the concentrations of Pb2 and Br– in a saturated solution of PbBr2 in:
a) pure water (assume μ = 0).
b) a solution with an ionic strength of 0.010.
c) a solution with an ionic strength of 0.10.
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A liquid ink is yellow and placed in a cuvette, colored optical filters are placed infront of the LED light and the light hits the ink cuvette. The intensity of the fluorescence is recorded for each color of optical filter placed infront of the LED
Why is it that using a specific color optical filter shows maximum intensity and the rest of the colors considerably decrease the fluoresence emission? breifly explain
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