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A graduated cylinder is filled with water to a level of 40.0 ml. When a piece of copper is lowered into the cylinder, the water level rises to 63.4 mL. What is the volume of the copper sample? If the density of the copper is 8.9 g/cm^, what is its mass?
Do you agree? The copper displaces the given volume of water. Now $rho_"Cu"=8.90*g*cm^3$ OR $rho_"Cu"=8.90*g*mL^-1$, i.e. $1*mL-=1*cm^3$ But by definition, $rho_"density"="mass"/"volume"$ And thus $"mass"=rhoxx"volume"=8.90*g*cancel(mL^-1)xx23.4*cancel(mL)$ $=208.3*g$. Do you follow?
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It is said chemical and physical properties are closely linked. Why does a chemical change also cause a change in physical properties?
Different combinations of atoms have different physical properties. For instance, when iron rusts, its melting point lowers.
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A chemical compound requires 8 ounces of Chemical A and 12 ounces of Chemical B. A mixture contains 24 ounces of Chemical A and 30 ounces of Chemical B. How can you fix the mixture to make the chemical compound?
Since 8x3=24 and since 12x3=36 you need to add 6oz of chemical B to have 24oz of chemical A and 36oz of chemical B. Take 1/3 of the total mixture...
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Pure copper may be produced by the reaction of copper(I) sulfide with oxygen gas as follows: $Cu_2S(s) + O_2(g) -> 2Cu(s) + SO_2(g)$. What mass of copper(I) sulfide is required in order to prepare 0.650 kg of copper metal?
You have given the stoichiometric equation that represents reduction of cuprous sulfide: $Cu_2S(s) + O_2(g) rarr 2Cu(s) + SO_2(g)$ Sulfur is oxidized; copper and oxygen are reduced. $"Moles of copper"=(650*g)/(63.55*g*mol^-1)=10.3*mol$....
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Are there changes in the physical and chemical properties of a substance when it undergoes a physical change? Is the same true for chemical changes?
...i.e.. solid to liquid, liquid to gas...and vice versa. And certainly, , mass per unit volume, changes markedly upon a phase change between a condensed phase, solid or liquid, and...
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State the difference between a physical change and a chemical change, and list three indications that a chemical change has occurred. Which indication is most suggestive of a chemical reaction?
Physical changes are changes in the formation or state of molecules and atoms. The arrangement of the molecules and atoms is different after the change but the chemical composition of...
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A student investigated the reactions of copper carbonate and copper oxide with dilute hydrochloric acid. How can a sample of copper chloride crystals be made from copper carbonate and dilute hydrochloric acid?
$CuCO_3(s) + 2HCl(aq)rarrCuCl_2(aq) + CO_2(g)uarr + H_2O(l)$ Or........... $CuO(s) + 2HCl(aq)rarrCuCl_2(aq) + H_2O(l)$ For each acid base reaction the product is the beautiful blue-coloured $[Cu(OH_2)_6]^(2+)$ ion, which is commonly represented...
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Hydrogen was passed over heated 2g copper oxide till only copper was left. The mass of copper obtained was was 1.6 grams. What is the percentage of oxygen in copper oxide?
There is a loss of 0.4 grams. $ 2.0 -1.6$ = 0.4 grams $ 0.4/2.0 xx 100 $ = 20% The Hydrogen will combine with the Oxygen in...
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Copper will react with sulfur to form a copper sulfide, if 1.500g copper reacts with sulfur to form 1.880g of copper sulfide, what is the empirical formula of the copper sulfide?
The idea here is that you need to use the mass of copper and the mass of the copper sulfide to determine how much sulfur the produced compound contains, then...
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An oxide of copper contains 2.118 g of copper and 0.2666 g of oxygen. Another oxide of copper contains the same mass of copper but 0.5332 g of copper. What are the empirical formulas of the oxides?
The empirical formulas are $"Cu"_2"O"$ and $"CuO"$. Oxide 1 $color(white)(mmmmml)"Cu" +color(white)(m) "O" → "Oxide 1"$ $"Mass/g":color(white)(l) 2.118color(white)(ll) 0.2666$ Our job is to calculate the ratio of the moles of...
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