Midterm 1 Flashcards

Questions and Answers

What is the result of the following equation with the correct number of significant figures? (400-84125)/(0.0110+4.818910^4)+6.52810^-3

-1.73

What is the result of the following equation with the correct number of significant figures? (42.8841*3.29)+332.58

473

Explain the differences between a scientific law and a scientific theory.

A law is a pattern produced by data. A theory uses laws to base a testable hypothesis and it's never entirely true.

At liftoff, an orbiter and External Tank carry 3.1644 x 10^6 L of fuel. The density of the fuel was 1.14 g/cm³, what is the mass of the fuel in mg?

3.61*10^9 mg Signup and view all the answers

From the description below, identify the physical and chemical properties of sodium hypochlorite, NaClO. Sodium hypochlorite (NaClO) is unstable and can decompose explosively to chlorine gas. NaClO is a solid at room temperature and has a density of 1.11 g/cm³.

Physical properties: solid at room temperature, density of 1.11. Chemical properties: unstable and can decompose explosively to Cl gas. Signup and view all the answers

What is precision?

The degree to which repeated measurements show the same result. Signup and view all the answers

What is accuracy?

How close a measurement is to the true value. Signup and view all the answers

What are isotopes?

Same element with a different number of neutrons. Signup and view all the answers

Determine each of the following for an atom of tellurium-127: A) Mass number B) Atomic number C) Number of protons D) Number of neutrons E) Number of electrons

A) Mass number = 127 B) Atomic number = 52 C) Number of protons = 52 D) Number of neutrons = 75 E) Number of electrons = 52 Signup and view all the answers

Name each compound: A) Na3PO4 B) P4O10 C) Cu(NO3)

A) Na3PO4 = Sodium phosphate B) P4O10 = Tetraphosphorus decoxide C) Cu(NO3) = Copper nitrate Signup and view all the answers

Write the formula for the compound or ions: A) Copper(II) nitride B) Dinitrogen tetroxide C) Iron(III) sulfate

A) Copper(II) nitride = Cu(NO2)2 B) Dinitrogen tetroxide = N2O4 C) Iron(III) sulfate = Fe2(SO4)3 Signup and view all the answers

The distance between two atoms in a molecule is 5.470*10^-9 inches. What is the distance in units of picometers?

138.9 pm Signup and view all the answers

Arrange the atoms and ions in order of increasing number of electrons: 40^K, 50^V^+, 53^Mn^4+

K, V^+, Mn^4+ Signup and view all the answers

In a lab, you are given an aqueous solution of an unknown salt that contains Pb^2+ and Ba^2+. Which of the following aqueous salts could be added to precipitate out the Pb^2+ ions but not the barium ions?

KCl Signup and view all the answers

What is the net ionic equation for the following reaction? K3PO4(aq) + CaCl2(aq) -->

3Ca^2+(aq) + 2PO4^3-(aq) --> Ca3(PO4)2(s) Signup and view all the answers

What is the concentration of a 50.0 ml sample of H2SO4(aq) if 23.74 ml of 0.400 M NaOH(aq) was required to completely react with the H2SO4(aq)?

0.0950 Signup and view all the answers

Consider the following reaction: 2NO(g) + 5H2(g) --> 2NH3(g) + 2H2O(g). A reaction mixture initially contains 5 moles of NO and 10 moles of H2. How much (in moles) is present of each substance after the reaction goes to completion?

1 mol NO, 0 mol H2, 4 mol NH3, 4 mol H2O Signup and view all the answers

Combustion analysis of a hydrocarbon that only contains hydrogen and carbon produces 13.2 g CO2 and 1.80 g H2O. What is the empirical formula of the hydrocarbon?

C3H2 Signup and view all the answers

Study Notes

Significant Figures in Calculations

Example equation: ((400-84125)/(0.0110+4.8189 \times 10^4)+6.528 \times 10^{-3}) results in (-1.73).
Example equation: ((42.8841 \times 3.29)+332.58) results in (473).

Scientific Law vs. Theory

A scientific law describes a consistent, observable pattern in data.
A scientific theory explains phenomena using laws and can be tested but is subject to revision.

Fuel Mass Calculation

Given: (3.1644 \times 10^6 , L) of fuel with a density of (1.14 , g/cm^3).
Calculated mass of fuel: (3.61 \times 10^9 , mg).

Sodium Hypochlorite Properties

Physical properties: solid at room temperature, density of (1.11 , g/cm^3).
Chemical properties: unstable, can decompose explosively to chlorine gas.

Definitions of Precision and Accuracy

Precision: consistency of repeated measurements.
Accuracy: closeness of a measurement to its true value.

Isotopes

Isotopes are variants of the same element that differ in the number of neutrons.

Tellurium-127 Characteristics

Mass number: (127).
Atomic number: (52).
Number of protons: (52).
Number of neutrons: (75).
Number of electrons: (52).

Naming Compounds

(Na_3PO_4): sodium phosphate.
(P_4O_{10}): tetraphosphorus decoxide.
(Cu(NO_3)): copper nitrate.

Writing Chemical Formulas

Copper(II) nitride: (Cu_2N).
Dinitrogen tetroxide: (N_2O_4).
Iron(III) sulfate: (Fe_2(SO_4)_3).

Atomic Distance Conversion

Distance between atoms: (5.470 \times 10^{-9} , inches) is equivalent to (138.9 , pm).

Electron Count of Atoms and Ions

Atoms/Ions in increasing order of electrons: (K^+, , V^{2+}, , Mn^{4+}).

Precipitation Reactions

To precipitate lead ions ((Pb^{2+})) without affecting barium ions ((Ba^{2+})), add (KCl).

Net Ionic Equations

Net ionic equation for the reaction (K_3PO_4(aq) + CaCl_2(aq)): (3Ca^{2+}(aq) + 2PO_4^{3-}(aq) \rightarrow Ca_3(PO_4)_2(s)).

Concentration of H₂SO₄

Concentration calculation based on reaction with (NaOH): (0.0950 , M).

Reaction Completion Calculation

For the reaction (2NO(g) + 5H_2(g) \rightarrow 2NH_3(g) + 2H_2O(g)) with initial moles:
- Final amounts: (1 , mol , NO), (0 , mol , H_2), (4 , mol , NH_3), (4 , mol , H_2O).

Empirical Formula Determination

Combustion of a hydrocarbon producing (13.2g , CO_2) and (1.80g , H_2O) results in the empirical formula (C_3H_2).

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Description

This quiz features important mathematical calculations and scientific concepts, including the application of significant figures and the differences between scientific laws and theories. Test your understanding of these crucial topics as you prepare for your midterm exam.