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Questions in chemistry

[Answered] ACTION 12.19: INTERACTION OF SALTS WITH AIR AND MOISTURE A salt that gives off part of its water of crystallization when exposed to air is called: An example of such salt is A compound absorbs water from the atmosphere when exposed to air without forming a solution. An example of such a compound is A substance that absorbs so much water from the atmosphere that it dissolves to form a solution is called An example of such compound is

[Answered] Combustion of glucose ($C_6H_{12}O_6$) is the main source of energy for animal cells: $C_6H_{12}O_6(s) + 6O_2(g) \rightarrow 6CO_2(g) + 6H_2O(l) \quad \Delta G_{rxn}(37^{\circ}C) = -2872. kJ$ One of the most important uses to which this energy is put is the assembly of proteins out of amino acid building blocks. The Gibbs free energy of formation of one peptide bond, joining one amino acid to another, is $21 kJ/mol$. Suppose some cells are assembling a certain protein made of 81 amino acids. (Note that the number of peptide bonds in the protein will be one less than the number of amino acids.) Calculate the minimum mass of glucose that must be burned to assemble 650. $\mu$mol of this protein. Round your answer to 2 significant digits.

[Answered] The formula for pH is [tex]$pH =-\log \left[ H ^{+}\right]$[/tex], where [tex]$\left[ H ^{+}\right]$[/tex] is the hydrogen ion concentration. The pH of a fruit juice is 3.1. What is the hydrogen ion concentration of the juice? The hydrogen ion concentration [tex]$\left[ H ^{+}\right]$[/tex] is approximately ______ moles per liter. (Round to the nearest tenth.)

[Answered] A flask filled to the 25.0 mL mark contained 29.97 g of a concentrated salt-water solution. What is the density of the solution?

[Answered] What is the percent error of the data? | Trial # | Density | |---|---| | 1 | 10.34 | | 2 | 10.58 | | 3 | 10.62 | | Average | 10.51 |

[Answered] One brand of vinegar has a pH of 4.5. Another brand has a pH of 5.0. The equation for the pH of a substance is [tex]$pH = - \log [H^+]$[/tex], where [tex]$H^+$[/tex] is the concentration of hydrogen ions. What is the approximate difference in the concentration of hydrogen ions between the two brands of vinegar? A. [tex]$2.2 \times 10^{-5}$[/tex] B. [tex]$3.2 \times 10^{-1}$[/tex] C. [tex]$3.2 \times 10^1$[/tex] D. [tex]$6.8 \times 10^4$[/tex]

[Answered] What is the basic unit of matter? A. atom B. molecule C. gas D. compound

[Answered] In this equation, $H _2 SO _4$ (sulfuric acid) is speeding up the reaction. Based on the chemical notation, sulfuric acid is A. an ion B. a product C. a reactant D. a catalyst

[Answered] sodium nitrate + water $\rightarrow$ saturated solution At $40^{\circ} C$ 104 g + 100 g $\rightarrow$ 204 g At $40^{\circ} C$ 204 g of saturated solution contains 104 g of sodium nitrate 25.5 g of saturated solution contains =? $\begin{array}{l} =\frac{25.5g \times 104g}{204g} \\ =13.00 g \end{array}$

[Answered] Convert the temperature of dry ice, $-77.0^{\circ} C$, into ${ }^{\circ} F$. $[?]{ }^{\circ} F$