Chemistry Measuring Techniques & Concepts

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Questions and Answers

When multiplying two numbers in scientific notation, what is the correct method for handling the exponents?

Multiply the exponents

Add the exponents (correct)

Subtract the exponents

Leave the exponents unchanged

Which of the following is the proper result when converting 38.7 × 10² to scientific notation?

3.87 × 10³ (correct)

38.7 × 10²

0.387 × 10⁴

387 × 10⁰

What will be the exponent of 10 when you multiply (6.022 × 10²³) and (6.42 × 10⁻²)?

21 (correct)

Which expression correctly represents the division of (6.63 × 10⁻²) by (6.0 × 10⁻²)?

1.105 × 10⁰ Signup and view all the answers

If you perform the operation (6.022 × 10²³) ÷ (6.42 × 10⁻²), what would be the value of the exponent on the 10 in the result?

23 Signup and view all the answers

What is the scientific notation of the number 637.8?

6.378 × 10^2 Signup and view all the answers

Which of the following represents the number 0.0479 in scientific notation?

4.79 × 10^-2 Signup and view all the answers

How would you express the number 0.00032 in scientific notation?

3.2 × 10^-4 Signup and view all the answers

What is the correct conversion of 12,378 to scientific notation?

1.2378 × 10^4 Signup and view all the answers

Which of the following correctly adds the exponents: $ (2.0 × 10^3) + (3.5 × 10^4) $?

5.5 × 10^4 Signup and view all the answers

In terms of scientific notation, what is the result of $ (6.0 × 10^2) ÷ (3.0 × 10^1) $?

2.0 × 10^1 Signup and view all the answers

What is the scientific notation for the number 2002.080?

2.00208 × 10^3 Signup and view all the answers

What is the proper scientific notation for 61.06700?

6.1067 × 10^1 Signup and view all the answers

What is the result of dividing $1.67 imes 10^{-24}$ by $9.12 imes 10^{-28}$?

$0.183 imes 10^{-4}$ Signup and view all the answers

What happens to the exponent when converting $0.183 imes 10^{4}$ to standard scientific notation?

The exponent becomes 3, increasing by 1. Signup and view all the answers

In the multiplication of $6.63 imes 10^{-34}$ and $6.0 imes 10^{-2}$, what is the combined exponent?

$10^{-36}$ Signup and view all the answers

When combining the terms $1.67 imes 10^{-24}$ and $9.12 imes 10^{-28}$ in division, what is the exponent in the final answer?

$-32$ Signup and view all the answers

What is the correct interpretation of $8.52 imes 10^{-39}$ when dividing by $39.78$?

The result will increase the exponent to $-38$. Signup and view all the answers

In the expression $1.67 imes 10^{-24} imes 9.12 imes 10^{-28}$, what is added to the exponent during multiplication?

The exponent of $10^{-4}$. Signup and view all the answers

How do you express $39.78 imes 10^{-34}$ in scientific notation?

$3.978 imes 10^{-33}$ Signup and view all the answers

What is the overall process when converting $0.183 imes 10^{4}$ to standard scientific notation?

Move decimal left, decrease exponent by 1. Signup and view all the answers

Study Notes

Chapter Overview

Chemistry is quantitative, dealing with quantities that have amounts and units.
Taking measurements is crucial in chemistry.
Scientific notation is a system to express large/small numbers.
Significant figures indicate precision in a measurement.
Problem-solving involves unit conversions and multi-step calculations.
Units raised to a power are also used in various contexts.
Density is a key concept relating mass to volume.

Taking Measurements

Quantities are expressed using a number and a unit.
Measurements involve numerical and unit specification.
Example: 5 kilometers specifies a distance.
Proper quantity expression involves both a number and a unit.

Scientific Notation

Expresses very large/small numbers concisely as N x 10ⁿ.
N must be a number ≥ 1 and < 10.
n is an integer that represents how many places the decimal point is moved.
Leftwards shift yields positive n; rightwards shift yields negative n.

Significant Figures

Indicate the precision of measurements.
Certain digits are always significant.
Uncertain (estimated) digits are final significant digits.
Zeros between non-zero digits are significant.
Leading zeros (before the first non-zero digit) are not significant.
Trailing zeros (after non-zero digits) are significant only when a decimal point is present.
Calculations reflect the least precise measurement.
Significant figures are used in calculations to avoid overstating the accuracy of results.

Significant Figures in Calculations

Addition/subtraction: Limit the final answer's significant figures to the column where all the numbers align.
Multiplication/division: Report the final answer's significant figures to the least number of significant figures in any of the initial numbers.
Rounding rules ensure accuracy without exaggerating precision.

Basic Units of Measurement

Metric system is based on multiples of 10.
SI units (International System of Units) are the preferred system of units for scientific measurements.
Each SI unit is based on a single base quantity.
Example include: meter (length), kilogram (mass), kelvin (temperature), second (time), mole (amount of substance), ampere (electric current), and candela (luminous intensity).

Problem Solving & Unit Conversions

Conversion factors relate different units of measurement.
Dimensional analysis uses conversion factors to cancel unnecessary units and obtain the required units.
Multi-step conversions involve using multiple conversion factors in a systematic fashion.

Units Raised to a Power

Power of 10 in a unit represents the power of 10 for both the number and the unit (e.g., square meters (m²)).
Conversion factors should consider the power when converting between units with powers.

Density

Density is mass per unit volume.
Density (ρ) = mass (m) / volume (V).
Density is constant for a given substance, irrespective of sample size.
Density is a ratio of units: g/cm³ or kg/L.
Density can be used as a conversion factor between mass and volume.

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Description

This quiz covers essential concepts in chemistry, focusing on measurements, scientific notation, significant figures, and density. It is designed to test your understanding of how to accurately express quantities, the use of scientific notation for large and small numbers, and the importance of precision in measurements.