GuideFoot - Learn Together, Grow Smarter. Logo

Questions in chemistry

📝 Answered - 5.5 500 g of Al₂(SO₄)₃ is dissolved in 2 dm³ water. 5.5.1 Define the term concentration. (2) 5.5.2 Calculate the concentration of the solution. (4)

📝 Answered - If the products of a reaction are $CO _2$ and $2 H _2 O$, what is known about the reactants? A. The reactants include $CO _2$ and $H _2 O$. B. The reactants include substances with only $C , O$, and H atoms. C. The reactants do not include any $C , O$, or H atoms. D. The reactants are also $CO _2$ and $H _2 O$.

📝 Answered - Select all the correct answers. Which statements correctly match a chemical name with its formula? Use the list of polyatomic ions and the periodic table to help you answer. A. The chemical formula for ammonium carbonate is $NH_4HCO_3$. B. The chemical formula for ammonium hypochlorite is $NH_4ClO$. C. The chemical formula for ammonium nitrate is $NH_4NO_3$. D. The chemical formula for ammonium phosphate is $NH_4(PO_4)_3$. E. The chemical formula for ammonium sulfate is $(NH_4)_2SO_3$.

📝 Answered - Which substance has [tex]$\Delta H f$[/tex] defined as [tex]$0 kJ / mol$[/tex] ? [tex]$H _2 O ( s )$[/tex] Ne (l) [tex]$F _2(g)$[/tex] [tex]$CO _2(g)$[/tex]

📝 Answered - Which of the following materials are irritants? A. Caustic soda B. Ethylene oxide C. Ethylbenzene D. Dichloromethane or "DCM" E. Turpentine

📝 Answered - Which of the following is the best definition of a physical change? A. A change in a substance with no new substances being formed B. A change in a substance in which mass is conserved C. A change in a substance where a new substance is formed D. A change in a substance in which bonds are broken

📝 Answered - Encircle T if the statement is true and F if it is false. 1. All mixtures are beneficial to humans. 2. Expiration dates placed in food and medicine must not be taken seriously. 3. Trails of plastic bags found in oceans is an example of a harmful form of mixture. 4. Researching about the substances that will be used in forming mixtures is not important. 5. An alloy is a type of solution made from combining two or more substances or metals.

📝 Answered - A. Fill in the blanks: 1. Substances that taste sour are generally ________. 2. A base has a ________ taste and feels ________. 3. ________ paper is used to determine whether a substance is acidic or basic. 4. Bases turn litmus paper to blue. B. Write True or False: 1. All acids taste bitter. 2. Bases are usually slippery to touch. 3. Vinegar is an example of a base. 4. Salt and water are the products of a neutralization reaction. C. Tick (/) the correct answer: 1. Which of these is a common household base? (a) Vinegar (b) Baking soda (c) Lemon juice (d) Water 2. What colour does blue litmus paper turn in the presence of an acid? (a) Red (b) Blue (c) Green (d) Yellow 3. Which of the following is an example of a neutral substance? (a) Salt (b) Baking soda (c) Lemon juice (d) Vinegar D. Match each term in Column A with the correct description in Column B. | Column A | Column B | |---|---| | 1. Acid | A. Changes colour in presence of acid or base | | 2. Base | B. Has a bitter taste and slippery feel | | 3. Neutralisation | C. Substance with a sour taste | | 4. Indicator | D. Reaction of acid with base | | 5. Salt | E. Product of neutralisation | E. Answer the following questions: 1. What is an indicator and why is it used in testing acids and bases? 2. Describe what happens to litmus paper when it is dipped into vinegar.

📝 Answered - 1. The substance which turns blue litmus red is (a) neutral (b) acidic (c) basic (d) alkaline 2. The acid present in curd/sour milk is (a) formic acid (b) acetic acid (c) lactic acid (d) hydrochloric acid 3. H₂SO₄ is (a) an acid (b) a salt (c) a base (d) an alkali

📝 Answered - 14. A complete combustion of a hydrocarbon forms 1.10 g of CO2 and 0.45 g of H2O. The molar mass is 84.00 g mol-1. Determine the empirical formula and molecular formula of the hydrocarbon.