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A sample of metal has a mass of [m] grams.  What is this mass in milligrams?

A solution has a mass of [x] grams, and a volume of [y] mL.  What is the density (g/mL) of this solution, reported to the correct number of significant digits?

An aqueous solution is found to have an H+ concentration of 7.8 x 10-2 M.  What is the concentration of OH- in this solution?

The following reaction is an example of an ___ reaction. 2 N2(g) + O2(g) → 2 N2O (g)             ΔHrxn = +163.2 kJ

What is the frequency of a photon of light with a wavelength of 615 nm?

Using VSEPR , fill in the table. Attach an image of your work- must be handwritten.  Lewis Dot Structure # bonded groups #lone pairs Molecular Shape CH4 CCl2O

A chemist carries out this reaction in the laboratory, using [x] grams of zinc and an excess of sulfur:  She isolated [y] g of ZnS. Zn + S –> ZnS   Using the balanced equation, calculate the percent yield the chemist retrieved from the reaction.   What is her percent yield for this reaction?   percent yield= (actual yield)/(theo yield) *100%

A 1.0 gram sample of a candy bar was placed in a bomb calorimeter with a heat capacity of 3.54 kcal/°C. The sample was completely burned, causing the temperature of the calorimeter to rise by 1.36 °C.   How many kilocalories of energy were stored in the candy bar?    Make sure to show all your work- No work = no credit

Identify each of these reactions as endothermic or exothermic: a) heat + H2O(l)  –> H2O  [reactionA]  b) H2O(g)  –> H2O(l) + heat [reactionB] c) K2CO3(s) –> K2CO3(aq) + heat [reactionC] d) heat+ NH4Cl(s) –> NH4Cl(aq) [reactionD] 

When solutions of potassium iodide and lead(II) nitrate are mixed, the result is potassium nitrate and lead(II) iodide.  This is an example of what type of reaction?    answer in all lower case