/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 17 Choose the word or phrase that b... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 7: Problem 17

Choose the word or phrase that best answers the question. Which is NOT evidence that a chemical reaction has occurred? A) Milk tastes sour. B) Steam condenses on a cold window. C) A strong odor comes from a broken egg. D) A slice of raw potato darkens.

Short Answer

Expert verified
Option B: Steam condenses on a cold window

Step by step solution

01

Understand the Concept

First, review what indicates a chemical reaction: change in color, production of gas, change in temperature, formation of a precipitate, emission of light, or change in odor.
02

Analyze Option A

Option A states 'Milk tastes sour.' This suggests a chemical change because the milk's composition has altered, likely due to fermentation.
03

Analyze Option B

Option B states 'Steam condenses on a cold window.' This describes a physical change, where water vapor turns into liquid. No new substances are formed.
04

Analyze Option C

Option C states 'A strong odor comes from a broken egg.' This suggests a chemical change, as the odor indicates a new substance (possibly hydrogen sulfide) is being released.
05

Analyze Option D

Option D states 'A slice of raw potato darkens.' This indicates a chemical change because the darkening is due to the formation of new compounds (oxidation).
06

Identify the Correct Answer

Only Option B refers to a physical change, not a chemical reaction. Therefore, it does NOT provide evidence of a chemical reaction.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Chemical Change
A chemical change occurs when a substance transforms into one or more new substances. This process involves a reorganization of atoms and the breaking or formation of chemical bonds.
Examples include:
  • Milk turning sour
  • Iron rusting
  • Burning wood
These changes are usually irreversible, and they often involve changes in physical properties like color, odor, and temperature. Remember, when a chemical change happens, a new substance with different properties is created.
Physical Change
A physical change affects the form of a substance, but does not alter its chemical composition. The substance remains the same, even though it may look different.
Examples include:
  • Ice melting into water
  • Tearing a piece of paper
  • Steam condensing on a cold window
These changes are usually reversible. Think about how you can freeze water, melt it, and then freeze it again鈥攊t remains H2O throughout the process.
Evidence of a Chemical Reaction
Identifying a chemical reaction can be tricky, but certain clues can help you out. Key indicators are:
  • Change in color
  • Production of gas
  • Change in temperature
  • Formation of a precipitate
  • Emission of light
  • Change in odor
Each of these signs points to the formation of new substances. For example, when you see bubbles forming in a liquid, it usually means a gas is being produced during a chemical reaction.
Change in Color
One of the most noticeable signs of a chemical reaction is a change in color. This happens because the new substances formed have different colors than the original ones.
Examples include:
  • A slice of raw potato darkening
  • Iron turning reddish-brown as it rusts
  • Leaves changing colors in the fall
A color change indicates that the substance's chemical makeup has changed, signaling a chemical reaction.
Production of Gas
The production of gas is another telltale sign of a chemical reaction. This can be observed as bubbles forming in a liquid.
Examples include:
  • Vinegar reacting with baking soda to produce carbon dioxide
  • Fermentation of milk producing lactic acid and gas
  • Combustion of fuel releasing gaseous products
If you see gas bubbles and there was no boiling involved, a chemical reaction is probably occurring.
Condensation
Condensation is a physical change where a gas transforms into a liquid. It happens when gas molecules slow down and clump together as the temperature drops.
Examples include:
  • Steam condensing on a cold window
  • Morning dew forming on grass
  • Water droplets forming on the outside of a cold beverage glass
Since condensation only changes the state of the substance (from gas to liquid) without altering its chemical structure, it is considered a physical change, not a chemical one.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Choose the word or phrase that best answers the question. Which of these reactions releases thermal energy? A) unbalanced B) balanced C) exothermic D) endothermic

Chili can be made using ground meat or chunks of meat. Which would you choose, if you were in a hurry? Explain.

Choose the word or phrase that best answers the question. Which statement about the law of conservation of mass is NOT true? A) The mass of reactants must equal the mass of products. B) All the atoms on the reactant side of an equation are also on the product side. C) The reaction creates new types of atoms. D) Atoms are not lost, but are rearranged.

Explain the differences between the vocabulary terms in each of the following sets. activation energy-rate of reaction

Choose the word or phrase that best answers the question. A balanced chemical equation must have the same number of which of these on both sides of the equation? A) atoms B) reactants C) molecules D) compounds
See all solutions

Recommended explanations on Physics Textbooks

Fluids

Read Explanation

Geometrical and Physical Optics

Read Explanation

Electromagnetism

Read Explanation

Fields in Physics

Read Explanation

Atoms and Radioactivity

Read Explanation

Waves Physics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.