Which of the following describes a substance in the solid physical state? The substance compresses significantly. The substance has a variable volume. The substance has a variable shape. all of the above none of the above
Which of the following is an example of a physical change? changing color releasing heat forming an insoluble solid dissolving a substance none of the above
Which of the following processes produces a decrease in the entropy of the system? D dissolution of solid KCI in water D melting ice to form water D boiling water to form steam mixing of two gases into one container D freezing water to form ice
Only about 25% of useful energy is produced in combustion (cars) True False
Question 2 Describe the difference between molecular and ionic compounds. square
Mixture A was made by mixing different components together but it appears to have one phase. Which term best categorizes mixture A? colloid solution emulsion suspension
Which of the following are the reactants of the chemical equation 2H_(2)+O_(2)... 2H_(2)O O_(2) C_(3)H_(13) H
Hexane, C_(6)H_(14) would have which of the following fragments in its mass spectrum? Check all that apply. (m)/(z)=32 (m)/(z)=57 (m)/(z)=29 (m)/(z)=43
Which neutral atom has the following electron configuration: 1s^22s^22p^63s^23p^64s^23d^104p^65s^24d^105p^66s^2 Enter the chemical symbol for the element. View Available Hint(s)
Calculate the density in grams per liter of HF at STP. Be sure your answer has the correct number of significant figures. Note: For molar mass calculations, round to the hundredths place. square (g)/(L)
10. Which types of bonds tend to have the highest bond energy? 11. Which types of bonds tend to have the lowest bond energy?
4 7 Add an answer item! Add an answer item! Answer Bank carbon iodine
10. What is the mole ratio of $MgCl_{2}$ to HCI $\underline {\quad }:\underline {\quad }$
Which action effectively increases the reactant concentration and increases the reaction rate? decreasing pressure heating the reactant mixture increasing pressure cooling the reactant mixture
Matter can undergo physical or chemical changes. Which of these are examples of chemical changes? Select TWO correct answers. A. Freezing water B. Milk souring C. Iron melting D. Dry ice sublimating E. Cooking an egg
What is the most common substance found in ecstasy? rat poison tar glass nicotine
Which action would speed up the reaction for the chemical reaction $CH_{3}Br+OH^{-}\rightarrow CH_{3}OH+Br^{-}$ increasing the $CH3Br$ concentration reducing the $OH-$ concentration cooling the reactant mixture reducing the pressure of the reactant mixture
Which action decreases the activation energy of a reaction? decreasing the temperature removing reactant molecules removing a catalyst adding a catalyst
Convert 89000 g $Pb(NO_{3})_{2}$ to atoms
Given the following reactions and corresponding $\Delta H$ values, find the $\Delta H$ (to the nearest whole \#) for the reaction: $H_{2}SO_{4}(l)\rightarrow SO_{3}(g)+H_{2}O(g)$ $H_{2}S(g)+2O_{2}(g)\rightarrow H_{2}SO_{4}(l)$ $\Delta H=-235kJ$ $H_{2}S(g)+2O_{2}(g)\rightarrow SO_{3}(g)+H_{2}O(l)$ $\Delta H=-207kJ$ $H_{2}O(l)\rightarrow H_{2}O(g)$ $\Delta H=44kJ$ $\square $
