Questions 64 and 65 Dental cements, which are used to fill cavities in teeth, are made by mixing a metal oxide powder with an acidic liquid. The metal oxide contains divalent ions, such as Ca2+, Mg2+ and Zn2+, or trivalent ions, such as AP+. The acidic liquid contains divalent anions, A2, or trivalent anions, A³- For example, metal ions, M2+, and divalent anions, A2-, form a dental cement of the form MA, as shown. MO powder + H₂A MA acidic dental liquid cement H₂O The figure shows the percentage by mass of evaporable and non-evaporable water in four dental cements at various times after mixing, and the compressive strength of the cements at these times. The hydration of a dental cement is the ratio of non-evaporable water to evaporable water. 64 ww% 20 zinc phosphate 15 10 zinc polycarboxylate Cevaporable non-evaporable silicate glass ionomer BAYYYY. Time (h) Compressive strength (MPa) 0 05 " 340 340 40 4 340 93 141 150 117 201 252 I Which one of the following represents the formula for a dental cement formed by reacting a trivalent metal ion with a divalent anion? 65 A M₂As B MA C M.A D ΜΑΣ Which one of the following is true based on the information given? The weakest cement is the most hydrated Zine cements are more hydrated than glass ionomers. B The hydration of cements increases with age. D As hydration increases, the compressive strength of the cement decreases
Questions 64 and 65 Dental cements, which are used to fill cavities in teeth, are made by mixing a metal oxide powder with an acidic liquid. The metal oxide contains divalent ions, such as Ca2+, Mg2+ and Zn2+, or trivalent ions, such as AP+. The acidic liquid contains divalent anions, A2, or trivalent anions, A³- For example, metal ions, M2+, and divalent anions, A2-, form a dental cement of the form MA, as shown. MO powder + H₂A MA acidic dental liquid cement H₂O The figure shows the percentage by mass of evaporable and non-evaporable water in four dental cements at various times after mixing, and the compressive strength of the cements at these times. The hydration of a dental cement is the ratio of non-evaporable water to evaporable water. 64 ww% 20 zinc phosphate 15 10 zinc polycarboxylate Cevaporable non-evaporable silicate glass ionomer BAYYYY. Time (h) Compressive strength (MPa) 0 05 " 340 340 40 4 340 93 141 150 117 201 252 I Which one of the following represents the formula for a dental cement formed by reacting a trivalent metal ion with a divalent anion? 65 A M₂As B MA C M.A D ΜΑΣ Which one of the following is true based on the information given? The weakest cement is the most hydrated Zine cements are more hydrated than glass ionomers. B The hydration of cements increases with age. D As hydration increases, the compressive strength of the cement decreases
Chemistry: Principles and Practice
3rd Edition
ISBN:9780534420123
Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Publisher:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer
Chapter14: Chemical Equilibrium
Section: Chapter Questions
Problem 14.84QE
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Transcribed Image Text:Questions 64 and 65
Dental cements, which are used to fill cavities in teeth, are made by mixing a metal oxide powder with an acidic
liquid. The metal oxide contains divalent ions, such as Ca2+, Mg2+ and Zn2+, or trivalent ions, such as AB+. The
acidic liquid contains divalent anions, A2, or trivalent anions, A3-
For example, metal ions, M2+, and divalent anions, A2-, form a dental cement of the form MA, as shown.
MO +
H₂A
MA
+
H₂O
powder
acidic
dental
liquid
cement
The figure shows the percentage by mass of evaporable and non-evaporable water in four dental cements at various
times after mixing, and the compressive strength of the cements at these times. The hydration of a dental cement
is the ratio of non-evaporable water to evaporable water.
64
ww%
20
20
15
10
zinc phosphate
zinc polycarboxylate
8 0
evaporable
non-evaporable
silicate
glass ionomer
vvvvvvvvvv
Time (h)
Compressive
xtrength (MPa)
0
0.5
40
340
93 141 150
40 62 75
117 201 252
T
Which one of the following represents the formula for a dental cement formed by reacting a trivalent metal
ion with a divalent anion?
65
^
MA
B
Map
C
MA
D
ΜΑ
Which one of the following is true based on the information given?
The weakest cement is the most hydrated
B
The hydration of cements increases with age.
Zine cements are more hydrated than glass ionomers.
As hydration increases, the compressive strength of the cement decreases
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