Check Atom Conservation - Middle School Physical Science
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What does a subscript change in a chemical formula: molecule count or atoms per molecule?
What does a subscript change in a chemical formula: molecule count or atoms per molecule?
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A subscript changes the number of atoms per molecule. Subscripts show atom ratios within one molecule/formula unit.
A subscript changes the number of atoms per molecule. Subscripts show atom ratios within one molecule/formula unit.
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Which is conserved in typical chemical reactions: total mass or total volume of gas?
Which is conserved in typical chemical reactions: total mass or total volume of gas?
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Total mass is conserved. Mass conservation follows from atom conservation; gas volumes can change.
Total mass is conserved. Mass conservation follows from atom conservation; gas volumes can change.
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Which side has more O atoms in $C + O_2
ightarrow CO$: reactants or products?
Which side has more O atoms in $C + O_2 ightarrow CO$: reactants or products?
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Reactants; O atoms are $2$ vs $1$ on products. $O_2$ provides $2$ O atoms; $CO$ uses only $1$ O atom.
Reactants; O atoms are $2$ vs $1$ on products. $O_2$ provides $2$ O atoms; $CO$ uses only $1$ O atom.
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Find and correct the missing coefficient to conserve O: $2H_2 + O_2
ightarrow H_2O$.
Find and correct the missing coefficient to conserve O: $2H_2 + O_2 ightarrow H_2O$.
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Use coefficient $2$: $2H_2 + O_2
ightarrow 2H_2O$. $O_2$ has $2$ O atoms that must equal products' $2×1=2$ O atoms.
Use coefficient $2$: $2H_2 + O_2 ightarrow 2H_2O$. $O_2$ has $2$ O atoms that must equal products' $2×1=2$ O atoms.
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Identify whether $2CO + O_2
ightarrow 2CO_2$ conserves atoms for C and O.
Identify whether $2CO + O_2 ightarrow 2CO_2$ conserves atoms for C and O.
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Yes; C: $2=2$, O: $4=4$. $2CO$ has $2$ C; $2CO_2$ has $2$ C. $2CO$ has $2$ O, $O_2$ has $2$ O (total $4$); $2CO_2$ has $2×2=4$ O.
Yes; C: $2=2$, O: $4=4$. $2CO$ has $2$ C; $2CO_2$ has $2$ C. $2CO$ has $2$ O, $O_2$ has $2$ O (total $4$); $2CO_2$ has $2×2=4$ O.
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Find the O atom totals in $CH_4 + 2O_2
ightarrow CO_2 + 2H_2O$ on each side.
Find the O atom totals in $CH_4 + 2O_2 ightarrow CO_2 + 2H_2O$ on each side.
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O totals: reactants $4$, products $4$. $2O_2$ has $2×2=4$ O; $CO_2$ has $2$ O and $2H_2O$ has $2×1=2$ O, total $4$.
O totals: reactants $4$, products $4$. $2O_2$ has $2×2=4$ O; $CO_2$ has $2$ O and $2H_2O$ has $2×1=2$ O, total $4$.
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Find the H atom totals in $CH_4 + 2O_2
ightarrow CO_2 + 2H_2O$ on each side.
Find the H atom totals in $CH_4 + 2O_2 ightarrow CO_2 + 2H_2O$ on each side.
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H totals: reactants $4$, products $4$. $CH_4$ has $4$ H; $2H_2O$ has $2×2=4$ H.
H totals: reactants $4$, products $4$. $CH_4$ has $4$ H; $2H_2O$ has $2×2=4$ H.
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Identify whether $N_2 + 3H_2
ightarrow 2NH_3$ conserves atoms for N and H.
Identify whether $N_2 + 3H_2 ightarrow 2NH_3$ conserves atoms for N and H.
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Yes; N: $2=2$, H: $6=6$. $N_2$ gives $2$ N; $2NH_3$ gives $2×1=2$ N. $3H_2$ gives $6$ H; $2NH_3$ gives $2×3=6$ H.
Yes; N: $2=2$, H: $6=6$. $N_2$ gives $2$ N; $2NH_3$ gives $2×1=2$ N. $3H_2$ gives $6$ H; $2NH_3$ gives $2×3=6$ H.
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Identify whether $H_2 + O_2
ightarrow H_2O$ conserves atoms by counting O atoms.
Identify whether $H_2 + O_2 ightarrow H_2O$ conserves atoms by counting O atoms.
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No; O atoms are $2$ on reactants and $1$ on products. $O_2$ has $2$ O atoms; $H_2O$ has only $1$ O atom.
No; O atoms are $2$ on reactants and $1$ on products. $O_2$ has $2$ O atoms; $H_2O$ has only $1$ O atom.
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Identify the conserved count for $2H_2 + O_2
ightarrow 2H_2O$: how many O atoms on each side?
Identify the conserved count for $2H_2 + O_2 ightarrow 2H_2O$: how many O atoms on each side?
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$2$ O atoms on each side. $O_2$ gives $2$ O; $2H_2O$ gives $2×1=2$ O.
$2$ O atoms on each side. $O_2$ gives $2$ O; $2H_2O$ gives $2×1=2$ O.
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Identify the conserved count for $2H_2 + O_2
ightarrow 2H_2O$: how many H atoms on each side?
Identify the conserved count for $2H_2 + O_2 ightarrow 2H_2O$: how many H atoms on each side?
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$4$ H atoms on each side. $2H_2$ gives $2×2=4$ H; $2H_2O$ gives $2×2=4$ H.
$4$ H atoms on each side. $2H_2$ gives $2×2=4$ H; $2H_2O$ gives $2×2=4$ H.
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Which option is allowed in a correct model: splitting atoms, merging atoms, or breaking bonds?
Which option is allowed in a correct model: splitting atoms, merging atoms, or breaking bonds?
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Breaking and forming bonds is allowed; atoms do not split or merge. Chemical reactions rearrange atoms via bond changes only.
Breaking and forming bonds is allowed; atoms do not split or merge. Chemical reactions rearrange atoms via bond changes only.
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What is the correct conclusion if any element’s atom count differs between reactants and products?
What is the correct conclusion if any element’s atom count differs between reactants and products?
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The model does not conserve atoms (the equation is unbalanced). Unequal counts violate conservation laws; balancing is needed.
The model does not conserve atoms (the equation is unbalanced). Unequal counts violate conservation laws; balancing is needed.
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What is the correct conclusion if each element’s atom count matches in reactants and products?
What is the correct conclusion if each element’s atom count matches in reactants and products?
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The model shows atom conservation (the equation is balanced). Equal atom counts verify the law of conservation of mass.
The model shows atom conservation (the equation is balanced). Equal atom counts verify the law of conservation of mass.
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What does conservation of atoms mean when comparing reactant and product particle models?
What does conservation of atoms mean when comparing reactant and product particle models?
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Each element has the same number of atoms before and after the reaction. Matter cannot be created or destroyed in chemical reactions.
Each element has the same number of atoms before and after the reaction. Matter cannot be created or destroyed in chemical reactions.
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Identify what a coefficient changes in a model: atoms inside a molecule or number of molecules?
Identify what a coefficient changes in a model: atoms inside a molecule or number of molecules?
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A coefficient changes the number of molecules (or formula units). Coefficients multiply entire formulas, not individual atoms.
A coefficient changes the number of molecules (or formula units). Coefficients multiply entire formulas, not individual atoms.
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Which feature in a particle model usually identifies different elements: color or position?
Which feature in a particle model usually identifies different elements: color or position?
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Color (or a distinct symbol) identifies different elements. Position shows arrangement; visual differences show element types.
Color (or a distinct symbol) identifies different elements. Position shows arrangement; visual differences show element types.
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What is the first step to verify atom conservation using reactant and product models?
What is the first step to verify atom conservation using reactant and product models?
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Count atoms of each element on both sides and compare totals. Systematic counting ensures no atoms are missed or double-counted.
Count atoms of each element on both sides and compare totals. Systematic counting ensures no atoms are missed or double-counted.
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Which statement best describes atoms in a chemical reaction: created, destroyed, or rearranged?
Which statement best describes atoms in a chemical reaction: created, destroyed, or rearranged?
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Atoms are rearranged into new combinations. Chemical reactions only break/form bonds between existing atoms.
Atoms are rearranged into new combinations. Chemical reactions only break/form bonds between existing atoms.
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What must stay the same in a chemical reaction model: number of atoms, atom sizes, or element types?
What must stay the same in a chemical reaction model: number of atoms, atom sizes, or element types?
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Number of atoms of each element and the element types must stay the same. Atoms rearrange but don't appear/disappear; sizes may vary in models.
Number of atoms of each element and the element types must stay the same. Atoms rearrange but don't appear/disappear; sizes may vary in models.
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What is the correct first step to verify atom conservation using particle models?
What is the correct first step to verify atom conservation using particle models?
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Count each element’s atoms in reactants and in products. Systematic counting ensures accurate verification of conservation.
Count each element’s atoms in reactants and in products. Systematic counting ensures accurate verification of conservation.
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Which statement is correct: atoms are created, destroyed, or rearranged in chemical reactions?
Which statement is correct: atoms are created, destroyed, or rearranged in chemical reactions?
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Atoms are rearranged; they are not created or destroyed. This follows the law of conservation of mass.
Atoms are rearranged; they are not created or destroyed. This follows the law of conservation of mass.
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Identify what a coefficient in a chemical equation represents in a particle model.
Identify what a coefficient in a chemical equation represents in a particle model.
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The number of molecules or formula units shown for that substance. Coefficients multiply entire formulas in balanced equations.
The number of molecules or formula units shown for that substance. Coefficients multiply entire formulas in balanced equations.
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What does a subscript in a chemical formula represent in a particle model?
What does a subscript in a chemical formula represent in a particle model?
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The number of atoms of that element in one molecule or formula unit. Subscripts show atom ratios within compounds.
The number of atoms of that element in one molecule or formula unit. Subscripts show atom ratios within compounds.
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What is the formula to find total atoms of an element from coefficient and subscript?
What is the formula to find total atoms of an element from coefficient and subscript?
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Total atoms $=$ coefficient $ imes$ subscript (use subscript $=1$ if none). Multiply to find total atoms when counting for conservation.
Total atoms $=$ coefficient $ imes$ subscript (use subscript $=1$ if none). Multiply to find total atoms when counting for conservation.
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