chapter 7 science -Tess

How many atoms are present in 2 moles of sodium

1.20x10 / 24 atom Na

How many grams of CaCO3 are in 2.7 mol of the compound

270g

What is a balanced chemical equation for the synthesis of NaBr from Na and Br2

2Na+Br2→2NaBr

Write a chemical equation that accurately represents what happens when sulfur and oxygen react to form sulfur trioxide

2S+3O2→2SO3

For the chemical reaction H2+CO2→H2O+CO, energy contained in the reactants is 352kJ and the energy contained in the products is 394kJ ,assuming 1 mol of each substance is present. How much energy is released or absorbed and is the reaction endothermic or exothermic

42kJ,endothermic

When iron metal reacts with oxygen the reaction can form Fe2O3. Write a balanced chemical equation for this reaction

4Fe+3O2→2Fe2O3

Single replacement reactions can take place with nonmetals In the following equation assume that A and C are nonmetals and B is a metal Complete the following general equation for the replacement of a non metal in a compund by another nonmetal A+BC→

BA+C

Methane Ch4 burns in oxygen gas to form water and carbon dioxide What is the correct balanced chemical equation for this reaction

CH4+2O2→2H2O+CO2

Cu+HNO3-→Cu(NO3)2+NO2+H2O

Cu+4HNO3→Cu(NO3)2+2NO2+2H2O

Hydrochloric acid HCl is added to solid NaOH After the reaction is complete NaCl dissolved in water remains.what are the products of this chemical reaction

NaCl and H2O

The element________is always present in a combustion reaction

Oxygen

Measuring how quickly a reactant disappears is one way to measure the____of the reaction

Rate

In a double replacement reaction there are two reactants and______products

Two

In a compound, chemical energy is contained in the

bonds

What happens to the bonds during a chemical reaction

breaking of chemical bonds in the reactants and the formation of chemical bonds in the products

a__________is the number that appears before a formula in a chemical equation

coefficient

The statement that in chemical reactions, the total mass of the reactants equals the total mass of the products, is the law of

conservation of mass

The total amount of energy before and after a chemical reaction is the same thus energy is___

conserved

When magnesium carbonate MgCO2 reacts with nitric acid HNO3 magnesium nitrate and carbonic acid form. Carbonic acid then breaks down into water and carbon dioxide. Which two types of reactions take place in this process

double replacement and decomposition

What happens to electrons during a redox reaction

electrons are gained and lost

In a chemical reaction an iron atom became the ion Fe2+.What happened to the iron atom

electrons are lost and oxidixed

in the terms of energy, the general chemical equationAB + CD + energy→AD+CB represents____________reaction

endothermic

When the forward and reverse paths of a change occur at the same rate the system is said to be in

equilibrium

In the terms of energy how would you classify the following chemical reaction 2Cu+O2→2CuO+315kJ

exothermic

During a chemical reaction ,energy is released during the_______of chemical bonds

formation

In general if the temperature of a chemical reaction is increased ,what happens to the reaction rate

increases

The coefficient in a balanced chemical equation always can express the ratio of

moles of reactants and products

The substances that are formed as a result of a chemical reaction are called

products

For the chemical reaction C2H6+137kJ→C2H4+H2 the chemical energy of the _____is greater than the chemical energy of the _____

products,reactants

for a certain chemical reaction, the reactants contain 390 kJ of chemical energy ,and the products contain 362 kJ of chemical energy. In order for energy to be conserved 28 kJ of energy must be

released

What does the arrow mean in a chemical equation

yields