Chemical Reactions Test Period 1

A chemical reaction occurs when bonds between atoms are broken and rearranged to form new chemicals. This process involves a change in the chemical composition of the substances involved, resulting in the formation of different molecules or compounds. Unlike a physical change, which only affects the physical properties of a substance (such as its shape or state), a chemical reaction involves a transformation at the molecular level. Therefore, the correct answer is Chemical Reaction.

It is colder than the other two because the reaction is happening at a slower rate

At a higher concentration, the reaction rate is faster because there are more reactant particles present, leading to more frequent collisions between them. This results in a greater amount of products being formed in a shorter period of time.

The given reaction is a synthesis reaction because it involves the combination of two reactants (N2 and H2) to form a single product (NH3). In a synthesis reaction, two or more substances combine to form a more complex substance.

This is a decomposition because the image shows a larger substance being broken down into smaller substances

Chemists need to work with balanced equations because of the law of conservation of mass. This law states that matter cannot be created or destroyed in a chemical reaction, only rearranged. Balanced equations ensure that the number of atoms of each element on both sides of the equation is the same, thus demonstrating the conservation of mass. By working with balanced equations, chemists can accurately calculate the amounts of reactants and products involved in a reaction and predict the outcome of chemical reactions.

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This reaction is a double replacement reaction because the cations and anions in the reactants switch places to form new compounds. In this case, the aluminum hydroxide (Al(OH)3) reacts with hydrogen bromide (HBr) to form aluminum bromide (AlBr3) and water (H2O).

In a chemical change, bonds between atoms are broken and new bonds are formed, resulting in the rearrangement of atoms to form new substances. This is different from a physical change where the arrangement of atoms remains the same and no new substances are formed. The statement correctly explains that in a chemical change, bonds are broken and atoms are rearranged, highlighting the key difference between a physical change and a chemical reaction.

The given correct answer is "exothermic." This means that the reaction releases heat energy into its surroundings. In the case of the heaters in Army MRE's, when water is added to the heater, a chemical reaction occurs that produces heat. This heat is then transferred to the food, making it hot and delicious.

Using a crushed tablet in warm water would result in the fastest dissolution of Alka Seltzer. Crushing the tablet increases the surface area, allowing for more contact between the water and the tablet, which speeds up the dissolution process. Warm water also increases the kinetic energy of the water molecules, causing them to move more quickly and collide with the tablet more frequently. This increased collision rate further enhances the dissolution rate. Therefore, using a crushed tablet in warm water would maximize the rate of dissolution and enable the medicine to enter the body more quickly.

This reaction is a double replacement reaction because the cations (K+ and H+) and the anions (OH- and Br-) in the reactants switch places to form new compounds (KBr and H2O) in the products.

At the 20-second mark of the experiment, a magical reaction occurs. Based on the given options, the correct answer is "endothermic." This means that the reaction absorbs heat from its surroundings. In an endothermic reaction, the energy of the products is higher than the energy of the reactants, resulting in a decrease in temperature. Therefore, at the 20-second mark, the reaction is likely absorbing heat, indicating an endothermic process.

In this reaction, lithium (Li) replaces hydrogen (H) in water (H2O) to form lithium hydroxide (LiOH) and hydrogen gas (H2). This is a single replacement reaction because one element (Li) replaces another element (H) in a compound (H2O).

C 3 C 1,3
H 8 H 8
O 2,10 O 10

The given chemical equation represents the combustion of C10H22 (a hydrocarbon) with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). Combustion reactions involve the rapid combination of a fuel (in this case, C10H22) with oxygen, resulting in the release of energy in the form of heat and light. Therefore, the correct answer is combustion.

Al 1,2 Al 2
O 7,10,18 O 13,16,18
H 8,12 H 2,8,12
S 1,3 S 3

The answer is surface area because a substance broken down into smaller chips would have a greater surface area making the reaction happen faster

you must DECREASE the pressure in order to increase the reaction rate. This is because decreasing the pressure will allow for the particles to move faster and contact each other more often

Colorado because the pressuere would be less