Chemistry

1. What is electronegativity? a. An atom's distance from the nucleus to its valence electron cloud b. The amount of energy needed to remove a valence electron c. The trend of how many electrons are in the outermost ring d. The ability to be able to gain electrons to reach stability

A(n) __ is matter composed of two or more substances that can be separated by physical means. element substance mixture compound

5. According to nutritional guidelines from the US Department of Agriculture, the estimated average requirement for dietary potassium is 4.7 g. What is the estimated average requirement of potassium in moles?

If a reaction is first order with a rate constant of $0.0450$ $s^{-1}$ how much time is required for $75\% $ of the initial quantity of reactant to be consumed? Answer: $\square $ S

Calculate the percent yield of $Br_{2}$ for the chemical reaction $2AgBr\rightarrow 2Ag+Br_{2}$ if the actual yield is 2.147 g and you start Ewith 6.234 g of AgBr.

1. What is the purpose of a Material Safety Data Sheet $(MSDS)$ 2. How should chemical spills be handled in the laboratory? 3. What personal protective equipment (PPE) is typically required in a lab setting? 4. What precautions should be taken when storing chemicals? 5. How should flammable materials be managed in the laboratory? 6. What is the appropriate response to a chemical exposure incident? 7. What are the signs of chemical exposure or poisoning? 8. How should waste chemicals be disposed of safely? 9. What is the first step to take when an accident occurs in the lab? 10. Why is it important to label all chemicals properly? 11. What protocols should be followed when working with hazardous substances? 12. How can one prevent cross -contamination in a laboratory? 13. How can one safely transport chemicals within a laboratory? 14. How often should safety equipment,like eyewash stations, be inspected? 15. What should you do if you discover an unlabeled chemical? 16. Why is it important to maintain good housekeeping in the lab? 17. What is the role of a safety officer in a laboratory? 18. What types of fire extinguishers should be available in a chemistry lab? 19. How can chemical reactions be monitored to ensure safety? 20. How important is it to report near misses or unsafe conditions in the laboratory?

Question 34 (1 point) Which of the following is an cxample of a molecule? $H_{2}O$ NaCl $CH_{4}$ All are examples of molecules

Data Sheet: A Sequence of Chemical Reactions:Transforming Copper Balance the following chemical reactions and record your observations for all the reactants and the products in each step. For each part observation there should be one observation per chemical Observations are changes in color,physical state, etc. Part 1: Nitric acid is added to copper metal: $\underline {\quad }Cu(s)+\underline {4}H_{3}O^{+}(aq)+\underline {2}\quad NO_{3}^{-}(aq)\rightarrow $ $\underline {\quad }[Cu(H_{2}O)_{6}]^{2+}(aq)+\underline {2}\quad NO_{2}(g)$ Appearance of reactants .Copper wire was shiny.brown, and thick. Nitric acid was colorless. Appearance of products:Nitric acid was green first, then light blue Evidence of a chemical reaction: Gas formation, color change, and yellow color gas production. Part 2: Sodium hydroxide is added to the aqueous copper solution: $\underline {\quad }(Cu(H_{2}O)_{4}^{2+}(aq)+\underline {2}OH^{-}(aq)\rightarrow \underline {\quad }Cu(OH)_{2}(s)+\underline {6}H_{2}O(l)$ Appearance of reactants: Clear light blue solution Appearance of products:Cloudy dark blue solution Evidence of a chemical reaction: Solution turned from light blue to dark blue Copper Transformation, Saint Joseph's University, Department of Chemistry

7. Acetylene $(C_{2}H_{2})$ is formed by reacting 7.08 g of C and 4.92 g of $H_{2}$ What is the limiting reactant? How much of the other reactant is in excess? (hint: calculate how much reacts and subtract from the starting amount) $2C(s)+H_{2}(g)\rightarrow C_{2}H_{2}(g)$

Classify the type of reaction represented by the following equation: $CoCl_{2}(aq)+2NaOH(aq)\rightarrow Co(OH)_{2}(s)+2NaCl(aq)$